[gthumb] Fixed error at configure time when using the -Werror flag

[Paolo Bacchilega <paobac src gnome org>]

commit c1cb4134bd3fe7757203bc840ea882ca5cb952fb
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sun Sep 26 18:01:04 2010 +0200

    Fixed error at configure time when using the -Werror flag
    
    Reset CFLAGS when checking for libraries.

 configure.ac |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 12b8beb..334ab19 100644
--- a/configure.ac
+++ b/configure.ac
@@ -147,8 +147,12 @@ AC_PATH_PROG(GLIB_MKENUMS, glib-mkenums)
 
 dnl ===========================================================================
 
+SAVE_CFLAGS="$CFLAGS"
+CFLAGS=""
 AC_CHECK_LIB(m, floor,, AC_MSG_ERROR([math library not found]))
 M_LIBS="-lm"
+CFLAGS="$SAVE_CFLAGS"
+unset SAVE_CFLAGS
 AC_SUBST(M_LIBS)
 
 dnl ===========================================================================
@@ -293,6 +297,8 @@ AC_ARG_ENABLE([jpeg],
 	      [AS_HELP_STRING([--disable-jpeg],[do not compile code that uses the libjpeg library])],,
 	      [enable_jpeg=yes])
 if test "x$enable_jpeg" = "xyes"; then
+	SAVE_CFLAGS="$CFLAGS"
+	CFLAGS=""
 	AC_CHECK_LIB(jpeg, jpeg_destroy_decompress,
         	     [enable_jpeg=yes],
 	     	     [enable_jpeg=no])
@@ -300,6 +306,8 @@ if test "x$enable_jpeg" = "xyes"; then
 		AC_DEFINE(HAVE_LIBJPEG, 1, [Define to 1 if libjpeg support is included])
 		JPEG_LIBS='-ljpeg -lm -lz'
 	fi
+	CFLAGS="$SAVE_CFLAGS"
+	usnet SAVE_CFLAGS
 fi
 AC_SUBST(JPEG_LIBS)
 AM_CONDITIONAL(ENABLE_JPEG_TOOLS, test "x$enable_jpeg" = xyes)
@@ -329,6 +337,8 @@ AC_ARG_ENABLE([tiff],
 	      [AS_HELP_STRING([--disable-tiff],[do not compile code that uses the libtiff library])],,
 	      [enable_tiff=yes])
 if test x$enable_tiff = xyes ; then
+	SAVE_CFLAGS="$CFLAGS"
+	CFLAGS=""
 	AC_CHECK_LIB(tiff, TIFFWriteScanline,
 		     [AC_CHECK_HEADER(tiffio.h,
 				      [enable_tiff=yes],
@@ -338,6 +348,8 @@ if test x$enable_tiff = xyes ; then
 		AC_DEFINE(HAVE_LIBTIFF, 1, [Define to 1 if libtiff support is included])
 		TIFF_LIBS='-ltiff -lm -lz'
 	fi
+	CFLAGS="$SAVE_CFLAGS"
+	unset SAVE_CFLAGS
 fi
 AC_SUBST(TIFF_LIBS)