gst-glib-gen.mak: make sure our generated *-enumtypes.c include config.h

This will be needed soon by the GST_*_API decorators.

gst-glib-gen.mak

@@ -31,7 +31,7 @@ $(glib_gen_basename)-enumtypes.h: $(glib_enum_headers)
 $(glib_gen_basename)-enumtypes.c: $(glib_enum_headers)
 	@if test "x$(glib_enum_headers)" = "x"; then echo "ERROR: glib_enum_headers is empty, please fix Makefile"; exit 1; fi
 	$(AM_V_GEN)$(GLIB_MKENUMS) \
-	--fhead "#include \"$(glib_gen_basename)-enumtypes.h\"\n$(enum_headers)" \
+	--fhead "#ifdef HAVE_CONFIG_H\n#include \"config.h\"\n#endif\n\n#include \"$(glib_gen_basename)-enumtypes.h\"\n$(enum_headers)" \
 	--fprod "\n/* enumerations from \"@filename@\" */" \
 	--vhead "GType\n@enum_name@_get_type (void)\n{\n  static volatile gsize g_define_type_id__volatile = 0;\n  if (g_once_init_enter (&g_define_type_id__volatile)) {\n    static const G@Type@Value values[] = {"     \
 	--vprod "      { @VALUENAME@, \"@VALUENAME@\", \"@valuenick@\" }," \