[glib] Fix CFLAGS manipulation

[Matthias Clasen <matthiasc src gnome org>]

commit ff9a61eed93ec342c00360e83abb4411647f64a2
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 20 08:16:09 2014 -0500

    Fix CFLAGS manipulation
    
    The code for ensuring that CFLAGS contain -g if
    --enable-debug has been specified did not work right.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=685204

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index e519cd1..9a79aa2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,7 +61,7 @@ AC_CONFIG_SRCDIR([glib/glib.h])
 AC_CONFIG_MACRO_DIR([m4macros])
 
 # Save this value here, since automake will set cflags later
-cflags_set=${CFLAGS+set}
+cflags_set=${CFLAGS:+set}
 
 AM_INIT_AUTOMAKE([1.11 -Wno-portability no-define no-dist-gzip dist-xz tar-ustar])
 AM_MAINTAINER_MODE([enable])
@@ -285,7 +285,7 @@ AC_SYS_LARGEFILE
 PKG_PROG_PKG_CONFIG(0.16)
 
 if test "x$enable_debug" = "xyes"; then
-  if test x$cflags_set != xset ; then
+  if test "x$cflags_set" != "x" ; then
       case " $CFLAGS " in
       *[[\ \   ]]-g[[\ \       ]]*) ;;
       *) CFLAGS="$CFLAGS -g" ;;