Revert "build/gmodule-2.0.pc: Move compiler flags from Libs to Cflags"

This reverts commit 004f48f4fc.

Per the discussion on #3356, this change was prompted by a
misunderstanding of ldflags/link_args, and it resulted in various other
packages using glib no longer getting symbols exported. This commit
restores the glib 2.76 behaviour.

gio/tests/meson.build

@@ -774,7 +774,7 @@ if not meson.is_cross_build()
 
     resource_plugin += shared_module('resourceplugin',
       sources: ['resourceplugin.c', plugin_resources_c],
-      c_args : export_dynamic_cflags,
+      link_args : export_dynamic_ldflags,
       dependencies : common_gio_tests_deps,
       install_dir : installed_tests_execdir,
       install_tag : 'tests',

gmodule/meson.build

@@ -115,24 +115,22 @@ pkg.generate(libgmodule,
   description : 'Dynamic module loader for GLib',
 )
 
-pkg.generate(libraries : [libgmodule],
+pkg.generate(libraries : [libgmodule, export_dynamic_ldflags],
   requires : ['glib-2.0'],
   version : glib_version,
   variables : [supported_var],
   install_dir : glib_pkgconfigreldir,
   filebase : 'gmodule-export-2.0',
-  extra_cflags : export_dynamic_cflags,
   name : 'GModule',
   description : 'Dynamic module loader for GLib',
 )
 
-pkg.generate(libraries : [libgmodule],
+pkg.generate(libraries : [libgmodule, export_dynamic_ldflags],
   requires : ['glib-2.0'],
   version : glib_version,
   variables : [supported_var],
   install_dir : glib_pkgconfigreldir,
   filebase : 'gmodule-2.0',
-  extra_cflags : export_dynamic_cflags,
   name : 'GModule',
   description : 'Dynamic module loader for GLib',
 )

meson.build

@@ -2328,15 +2328,15 @@ if host_system == 'windows'
   # Autotools explicitly removed --Wl,--export-all-symbols from windows builds,
   # with no explanation. Do the same here for now but this could be revisited if
   # if causes issues.
-  export_dynamic_cflags = []
+  export_dynamic_ldflags = []
 elif host_system == 'cygwin'
-  export_dynamic_cflags = ['-Wl,--export-all-symbols']
+  export_dynamic_ldflags = ['-Wl,--export-all-symbols']
 elif host_system in ['darwin', 'ios']
-  export_dynamic_cflags = []
+  export_dynamic_ldflags = []
 elif host_system == 'sunos'
-  export_dynamic_cflags = []
+  export_dynamic_ldflags = []
 else
-  export_dynamic_cflags = ['-Wl,--export-dynamic']
+  export_dynamic_ldflags = ['-Wl,--export-dynamic']
 endif
 
 win32_cflags = []