Fix nng-config.cmake setting missing NNG_PKGS, version info

The generated nng-config.cmake file wasn't including
dependencies (like Threads) causing the demos to not build properly on
systems relying on pthreads. Version info was also not being
populated, but it seems that's been the case for at least the last release.

cmake/nng-config.cmake.in

@@ -8,9 +8,9 @@
 
 @PACKAGE_INIT@
 
-set(NNG_VERSION_MAJOR "@NNG_VERSION_MAJOR@")
-set(NNG_VERSION_MINOR "@NNG_VERSION_MINOR@")
-set(NNG_VERSION_PATCH "@NNG_VERSION_PATCH@")
+set(NNG_VERSION_MAJOR "@NNG_MAJOR_VERSION@")
+set(NNG_VERSION_MINOR "@NNG_MINOR_VERSION@")
+set(NNG_VERSION_PATCH "@NNG_PATCH_VERSION@")
 
 set_and_check(NNG_INCLUDE_DIRS "@PACKAGE_INCLUDE_INSTALL_DIRS@")
 

src/CMakeLists.txt

@@ -90,6 +90,7 @@ write_basic_package_version_file("${version_config}"
         VERSION ${NNG_PACKAGE_VERSION}
         COMPATIBILITY SameMajorVersion
         )
+get_property(NNG_PKGS GLOBAL PROPERTY NNG_PKGS)
 configure_package_config_file(${PROJECT_SOURCE_DIR}/cmake/${PROJECT_NAME}-config.cmake.in "${project_config}"
         INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
         PATH_VARS INCLUDE_INSTALL_DIRS)

src/platform/posix/CMakeLists.txt

@@ -15,6 +15,7 @@ if (NNG_PLATFORM_POSIX)
 
     find_package(Threads REQUIRED)
     nng_link_libraries(Threads::Threads)
+    set_property(GLOBAL APPEND PROPERTY NNG_PKGS Threads)
 
     # Unconditionally declare the following feature test macros.  These are
     # needed for some platforms (glibc and SunOS/illumos) and are harmless
@@ -105,4 +106,4 @@ if (NNG_PLATFORM_POSIX)
     else ()
         nng_sources(posix_rand_urandom.c)
     endif ()
-endif ()
+endif ()

src/sp/transport/zerotier/CMakeLists.txt

@@ -29,6 +29,7 @@ if (NNG_TRANSPORT_ZEROTIER)
         ************************************************************")
 
     find_package(zerotiercore REQUIRED)
+    set_property(GLOBAL APPEND PROPERTY NNG_PKGS zerotiercore)
 
     nng_link_libraries(zerotiercore::zerotiercore)
     nng_defines(NNG_TRANSPORT_ZEROTIER)