Do not mix system and bdwgc headers in same include group

Issue #364 (bdwgc).

This is needed to prevent clang-format to change the order of included
header files where the order is important.

* cord/tests/de.c [WIN32]: Move include de_win.h down to be in
a separate include group (from that of windows.h).
* extra/AmigaOS.c: Place a blank line after include gc_priv.h.
* include/private/gc_priv.h [ANY_MSWIN]: Place a blank line between
include windows.h and winbase.h (and add a comment).
* pthread_stop_world.c [GC_ENABLE_SUSPEND_THREAD]: Place a blank line
between include sys/time.h and javaxfc.h; reformat comment.
* tests/gctest.c: Place a blank line between include gc.h and
javaxfc.h.
* tests/weakmap.c [GC_PTHREADS]: Move include errno.h and pthread.h
upper (to be in a separate include group).

cord/tests/de.c

@@ -49,7 +49,6 @@
 # endif
 # define NOSERVICE
 # include <windows.h>
-# include "de_win.h"
 #elif defined(MACINTOSH)
 # include <console.h>
 /* curses emulation. */
@@ -73,6 +72,10 @@
 # define de_error(s) { fprintf(stderr, s); sleep(2); }
 #endif
 
+#ifdef WIN32
+# include "de_win.h"
+#endif
+
 #include "de_cmds.h"
 
 #if defined(CPPCHECK)

extra/AmigaOS.c

@@ -4,6 +4,7 @@
 
 #if !defined(GC_AMIGA_DEF) && !defined(GC_AMIGA_SB) && !defined(GC_AMIGA_DS) && !defined(GC_AMIGA_AM)
 # include "private/gc_priv.h"
+
 # include <stdio.h>
 # include <signal.h>
 # define GC_AMIGA_DEF

include/private/gc_priv.h

@@ -287,6 +287,8 @@ typedef struct hblkhdr hdr;
 # endif
 # define NOSERVICE
 # include <windows.h>
+
+  /* This is included strictly after windows.h. */
 # include <winbase.h>
 #endif /* ANY_MSWIN */
 

pthread_stop_world.c

@@ -590,7 +590,9 @@ STATIC void GC_restart_handler(int sig)
 
 # ifdef GC_ENABLE_SUSPEND_THREAD
 #   include <sys/time.h>
-#   include "gc/javaxfc.h" /* to get the prototypes as extern "C" */
+
+    /* This is to get the prototypes as extern "C".     */
+#   include "gc/javaxfc.h"
 
     STATIC void GC_brief_async_signal_safe_sleep(void)
     {

tests/gctest.c

@@ -43,6 +43,7 @@
 # undef GC_NO_THREAD_REDIRECTS
 #endif
 #include "gc.h"
+
 #include "gc/javaxfc.h"
 
 /* Number of additional threads to fork. */

tests/weakmap.c

@@ -28,6 +28,11 @@
 
 #include <string.h>
 
+#ifdef GC_PTHREADS
+# include <errno.h> /* for EAGAIN, EBUSY */
+# include <pthread.h>
+#endif
+
 #undef rand
 /* Note: concurrent update of seed does not hurt the test.      */
 static GC_RAND_STATE_T seed;
@@ -41,8 +46,6 @@ static GC_RAND_STATE_T seed;
     /* This excludes the main thread, which also runs a test.   */
 #   define NTHREADS 5
 # endif
-# include <errno.h> /* for EAGAIN, EBUSY */
-# include <pthread.h>
 # include "private/gc_atomic_ops.h" /* for AO_t and AO_fetch_and_add1 */
 #else
 # undef NTHREADS