[gtk+] Fix automake warning about CFLAGS etc. being user variables

[John Ralls <jralls src gnome org>]

commit 655c781b6e0c0a6e755ea136e86fd7a3f11767c5
Author: John Ralls <jralls ceridwen us>
Date:   Mon Apr 22 15:48:03 2013 -0700

    Fix automake warning about CFLAGS etc. being user variables

 gtk/native/Makefile.am | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/gtk/native/Makefile.am b/gtk/native/Makefile.am
index 302f055..64899e9 100644
--- a/gtk/native/Makefile.am
+++ b/gtk/native/Makefile.am
@@ -1,8 +1,8 @@
 CC = @CC_FOR_BUILD@
-CFLAGS = @CFLAGS_FOR_BUILD@
+AM_CFLAGS = @CFLAGS_FOR_BUILD@
 CPP = @CPP_FOR_BUILD@
-CPPFLAGS = @CPPFLAGS_FOR_BUILD@
-LDFLAGS = @LDFLAGS_FOR_BUILD@
+AM_CPPFLAGS = @CPPFLAGS_FOR_BUILD@
+AM_LDFLAGS = @LDFLAGS_FOR_BUILD@
 
 if CROSS_COMPILING
 if !USE_EXTERNAL_ICON_CACHE