gl: Reorder CFLAGS to include in-source dirs first in examples

https://bugzilla.gnome.org/show_bug.cgi?id=733426

tests/examples/gl/sdl/Makefile.am

@@ -7,10 +7,13 @@ noinst_PROGRAMS += sdlshare
 
 sdlshare_SOURCES = sdlshare.c
 
-sdlshare_CFLAGS=$(GST_PLUGINS_BASE_CFLAGS)$(GST_CFLAGS) \
-    $(GL_CFLAGS) $(SDL_CFLAGS) \
+sdlshare_CFLAGS= \
 	-I$(top_srcdir)/gst-libs \
-	-I$(top_builddir)/gst-libs
+	-I$(top_builddir)/gst-libs \
+	$(GST_PLUGINS_BASE_CFLAGS) \
+	$(GST_CFLAGS) \
+	$(GL_CFLAGS) \
+	$(SDL_CFLAGS)
 sdlshare_LDADD= $(GST_LIBS) $(GL_LIBS) $(SDL_LIBS) \
 	$(top_builddir)/gst-libs/gst/gl/libgstgl-$(GST_API_VERSION).la \
 	-lgstvideo-$(GST_API_VERSION)