libjson-c: force json_c_ prefix on json-c namespace

Problem: json-c exports symbols like json_object_put()
that conflict with other JSON implementations we might
want to migrate to, such as jansson as discussed in flux-framework#301.

To avoid such conflicts with the embedded json-c library,
force all visible json-c text symbols to have a json_c_
prefix, by including a new header, namespace.h in the json-c
sources and the "public" json.h header.  namespace.h redefines
text symbols that do not already have a json_c_ prefix, e.g.
  #define json_object_put json_c_object_put

This allows any part of flux-core to independently migrate
to a new JSON implementation that has clashing symbols by simply
not including src/common/libjson-c/json.h.

src/common/libjson-c/Makefile.am

@@ -6,7 +6,8 @@ AM_LDFLAGS = \
 	$(CODE_COVERAGE_LDFLAGS)
 
 AM_CPPFLAGS = \
-	-I$(top_srcdir)
+	-I$(top_srcdir) \
+	-include $(srcdir)/namespace.h
 
 noinst_LTLIBRARIES = libjson-c.la
 
@@ -34,6 +35,7 @@ libjson_c_la_SOURCES = \
 	random_seed.c \
 	random_seed.h \
 	json.h \
-	json_inttypes.h
+	json_inttypes.h \
+	namespace.h
 
 EXTRA_DIST = AUTHORS COPYING

src/common/libjson-c/json.h

@@ -17,6 +17,7 @@
 extern "C" {
 #endif
 
+#include "namespace.h"
 #include "bits.h"
 #include "debug.h"
 #include "linkhash.h"

src/common/libjson-c/namespace.h

@@ -0,0 +1,111 @@
+#define array_list_add	json_c_array_list_add
+#define array_list_bsearch	json_c_array_list_bsearch
+#define array_list_del_idx	json_c_array_list_del_idx
+#define array_list_free	json_c_array_list_free
+#define array_list_get_idx	json_c_array_list_get_idx
+#define array_list_length	json_c_array_list_length
+#define array_list_new	json_c_array_list_new
+#define array_list_put_idx	json_c_array_list_put_idx
+#define array_list_sort	json_c_array_list_sort
+#define mc_debug	json_c_mc_debug
+#define mc_error	json_c_mc_error
+#define mc_get_debug	json_c_mc_get_debug
+#define mc_info	json_c_mc_info
+#define mc_set_debug	json_c_mc_set_debug
+#define mc_set_syslog	json_c_mc_set_syslog
+#define json_c_version	json_c_version
+#define json_c_version_num	json_c_version_num
+#define json_object_array_add	json_c_object_array_add
+#define json_object_array_bsearch	json_c_object_array_bsearch
+#define json_object_array_del_idx	json_c_object_array_del_idx
+#define json_object_array_get_idx	json_c_object_array_get_idx
+#define json_object_array_length	json_c_object_array_length
+#define json_object_array_put_idx	json_c_object_array_put_idx
+#define json_object_array_sort	json_c_object_array_sort
+#define json_object_double_to_json_string	json_c_object_double_to_json_string
+#define json_object_equal	json_c_object_equal
+#define json_object_free_userdata	json_c_object_free_userdata
+#define json_object_get	json_c_object_get
+#define json_object_get_array	json_c_object_get_array
+#define json_object_get_boolean	json_c_object_get_boolean
+#define json_object_get_double	json_c_object_get_double
+#define json_object_get_int	json_c_object_get_int
+#define json_object_get_int64	json_c_object_get_int64
+#define json_object_get_object	json_c_object_get_object
+#define json_object_get_string	json_c_object_get_string
+#define json_object_get_string_len	json_c_object_get_string_len
+#define json_object_get_type	json_c_object_get_type
+#define json_object_get_userdata	json_c_object_get_userdata
+#define json_object_is_type	json_c_object_is_type
+#define json_object_new_array	json_c_object_new_array
+#define json_object_new_boolean	json_c_object_new_boolean
+#define json_object_new_double	json_c_object_new_double
+#define json_object_new_double_s	json_c_object_new_double_s
+#define json_object_new_int	json_c_object_new_int
+#define json_object_new_int64	json_c_object_new_int64
+#define json_object_new_object	json_c_object_new_object
+#define json_object_new_string	json_c_object_new_string
+#define json_object_new_string_len	json_c_object_new_string_len
+#define json_object_object_add	json_c_object_object_add
+#define json_object_object_add_ex	json_c_object_object_add_ex
+#define json_object_object_del	json_c_object_object_del
+#define json_object_object_get	json_c_object_object_get
+#define json_object_object_get_ex	json_c_object_object_get_ex
+#define json_object_object_length	json_c_object_object_length
+#define json_object_put	json_c_object_put
+#define json_object_set_serializer	json_c_object_set_serializer
+#define json_object_set_userdata	json_c_object_set_userdata
+#define json_object_to_json_string	json_c_object_to_json_string
+#define json_object_to_json_string_ext	json_c_object_to_json_string_ext
+#define json_object_to_json_string_length	json_c_object_to_json_string_length
+#define json_object_userdata_to_json_string	json_c_object_userdata_to_json_string
+#define json_object_iter_begin	json_c_object_iter_begin
+#define json_object_iter_end	json_c_object_iter_end
+#define json_object_iter_equal	json_c_object_iter_equal
+#define json_object_iter_init_default	json_c_object_iter_init_default
+#define json_object_iter_next	json_c_object_iter_next
+#define json_object_iter_peek_name	json_c_object_iter_peek_name
+#define json_object_iter_peek_value	json_c_object_iter_peek_value
+#define json_tokener_error_desc	json_c_tokener_error_desc
+#define json_tokener_free	json_c_tokener_free
+#define json_tokener_get_error	json_c_tokener_get_error
+#define json_tokener_new	json_c_tokener_new
+#define json_tokener_new_ex	json_c_tokener_new_ex
+#define json_tokener_parse	json_c_tokener_parse
+#define json_tokener_parse_ex	json_c_tokener_parse_ex
+#define json_tokener_parse_verbose	json_c_tokener_parse_verbose
+#define json_tokener_reset	json_c_tokener_reset
+#define json_tokener_set_flags	json_c_tokener_set_flags
+#define json_object_from_fd	json_c_object_from_fd
+#define json_object_from_file	json_c_object_from_file
+#define json_object_to_file	json_c_object_to_file
+#define json_object_to_file_ext	json_c_object_to_file_ext
+#define json_parse_double	json_c_parse_double
+#define json_parse_int64	json_c_parse_int64
+#define json_type_to_name	json_c_type_to_name
+#define json_util_get_last_err	json_c_util_get_last_err
+#define json_global_set_string_hash	json_c_global_set_string_hash
+#define lh_abort	json_c_lh_abort
+#define lh_char_equal	json_c_lh_char_equal
+#define lh_kchar_table_new	json_c_lh_kchar_table_new
+#define lh_kptr_table_new	json_c_lh_kptr_table_new
+#define lh_ptr_equal	json_c_lh_ptr_equal
+#define lh_table_delete	json_c_lh_table_delete
+#define lh_table_delete_entry	json_c_lh_table_delete_entry
+#define lh_table_free	json_c_lh_table_free
+#define lh_table_insert	json_c_lh_table_insert
+#define lh_table_insert_w_hash	json_c_lh_table_insert_w_hash
+#define lh_table_length	json_c_lh_table_length
+#define lh_table_lookup	json_c_lh_table_lookup
+#define lh_table_lookup_entry	json_c_lh_table_lookup_entry
+#define lh_table_lookup_entry_w_hash	json_c_lh_table_lookup_entry_w_hash
+#define lh_table_lookup_ex	json_c_lh_table_lookup_ex
+#define lh_table_new	json_c_lh_table_new
+#define lh_table_resize	json_c_lh_table_resize
+#define printbuf_free	json_c_printbuf_free
+#define printbuf_memappend	json_c_printbuf_memappend
+#define printbuf_memset	json_c_printbuf_memset
+#define printbuf_new	json_c_printbuf_new
+#define printbuf_reset	json_c_printbuf_reset
+#define sprintbuf	json_c_sprintbuf
+#define json_c_get_random_seed	json_c_get_random_seed