make: use AM_CPPFLAGS rather than per-target libxcb_render_util_la_CPPFLAGS

There is only one target in this directory, so we do not need to trigger
the per-target infrastructure which would require AC_PROG_CC_C_O macro.
So libxcb_render_util_la-util.o simply becomes util.o.

http://www.gnu.org/software/automake/manual/automake.html#Renamed-Objects



Signed-off-by: Gaetan Nadon <memsize@videotron.ca>
Reviewed-by: Arnaud Fontaine <arnau@debian.org>

renderutil/Makefile.am

@@ -5,8 +5,8 @@ lib_LTLIBRARIES = libxcb-render-util.la
 
 xcbinclude_HEADERS = xcb_renderutil.h
 
+AM_CPPFLAGS = $(XCB_CFLAGS) $(XCB_RENDER_CFLAGS)
 libxcb_render_util_la_SOURCES = cache.c util.c glyph.c
-libxcb_render_util_la_CPPFLAGS = $(XCB_CFLAGS) $(XCB_RENDER_CFLAGS)
 libxcb_render_util_la_LIBADD = $(XCB_LIBS) $(XCB_RENDER_LIBS)
 libxcb_render_util_la_LDFLAGS = -no-undefined