* Also look for postprocess.h under libpostproc/

Upstream-status: Pending

--- a/configure.ac
+++ b/configure.ac
@@ -2589,7 +2589,7 @@ then
       VLC_SAVE_FLAGS
       CPPFLAGS="${CPPFLAGS} ${POSTPROC_CFLAGS}"
       CFLAGS="${CFLAGS} ${POSTPROC_CFLAGS}"
-      AC_CHECK_HEADERS(postproc/postprocess.h)
+      AC_CHECK_HEADERS(postproc/postprocess.h,[],[AC_CHECK_HEADERS(libpostproc/postprocess.h)])
       VLC_ADD_PLUGIN([postproc])
       VLC_RESTORE_FLAGS
     ],[