g-i: use only "ges/ges.h" as c-include for introspection

This is the only header which shall be included by user. Otherwise some
language using gir to generate binding, e.g Vala, will includes all
headers files in alphabetical order which causes compilation errors due
to incomplete type.

https://bugzilla.gnome.org/show_bug.cgi?id=765856

ges/Makefile.am

@@ -176,7 +176,6 @@ BUILT_GIRSOURCES = GES-@GST_API_VERSION@.gir
 
 gir_headers=$(patsubst %,$(srcdir)/%, $(libges_@GST_API_VERSION@include_HEADERS))
 gir_sources=$(patsubst %,$(srcdir)/%, $(libges_@GST_API_VERSION@_la_SOURCES))
-gir_cincludes=$(patsubst %,--c-include='ges/%',$(libges_@GST_API_VERSION@include_HEADERS))
 
 GES-@GST_API_VERSION@.gir: $(INTROSPECTION_SCANNER) libges-@GST_API_VERSION@.la
 	$(AM_V_GEN)PKG_CONFIG_PATH="$(GST_PKG_CONFIG_PATH)" \
@@ -185,7 +184,7 @@ GES-@GST_API_VERSION@.gir: $(INTROSPECTION_SCANNER) libges-@GST_API_VERSION@.la
 		--identifier-prefix=GES \
 		--symbol-prefix=ges \
 		--warn-all \
-		$(gir_cincludes) \
+		--c-include='ges/ges.h' \
 		-I$(top_srcdir) \
 		-I$(top_builddir) \
 		--add-include-path=`$(PKG_CONFIG) --variable=girdir gstreamer-@GST_API_VERSION@` \