[gtk-osx] Fix CFLAGS quoting for gmp on PPC.

[John Ralls <jralls src gnome org>]

commit 9e062276937586c3720d20fc4316b3ba4b4ead45
Author: John Ralls <jralls ceridwen us>
Date:   Sat Feb 28 13:20:18 2015 -0800

    Fix CFLAGS quoting for gmp on PPC.

 jhbuildrc-gtk-osx |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/jhbuildrc-gtk-osx b/jhbuildrc-gtk-osx
index 8d6b68a..85fd3b3 100644
--- a/jhbuildrc-gtk-osx
+++ b/jhbuildrc-gtk-osx
@@ -292,7 +292,7 @@ def setup_sdk(target, sdk_version, architectures=[_default_arch]):
         append_autogenargs("glib", "ac_cv_c_bigendian=no")
     elif architectures == ["ppc"]:
         append_autogenargs("glib", "ac_cv_c_bigendian=yes")
-        append_autogenargs("gmp", "CFLAGS=-force_cpusubtype_ALL $CFLAGS")
+        append_autogenargs("gmp", 'CFLAGS="-force_cpusubtype_ALL $CFLAGS"')
 
     # For unknown reasons, iconv is not picked up correctly without this
     #