[gimp] plug-ins: fix the build on OS X

[Kristian Rietveld <kristian src gnome org>]

commit 51d26b06db29116258d3e96858642067a7b0f062
Author: Kristian Rietveld <kris loopnest org>
Date:   Wed Sep 7 10:32:15 2016 +0200

    plug-ins: fix the build on OS X
    
    We need to have -xobjective-c specified only for compile commands
    that will perform compilation. Otherwise, for compile commands
    that only link the compiler interprets .o files as C source ...

 plug-ins/common/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plug-ins/common/Makefile.am b/plug-ins/common/Makefile.am
index be71353..318bedc 100644
--- a/plug-ins/common/Makefile.am
+++ b/plug-ins/common/Makefile.am
@@ -1769,7 +1769,7 @@ warp_LDADD = \
 
 web_browser_LDFLAGS = $(framework_cocoa)
 
-web_browser_CFLAGS = $(xobjective_c)
+web_browser_CPPFLAGS = $(AM_CPPFLAGS) $(xobjective_c)
 
 web_browser_SOURCES = \
        web-browser.c