commit 776757a23e9930588950c7fcbc7827ec7a3e51c4
Author: Tomáš Chvátal <tchvatal@suse.com>
Date:   Mon Jan 4 15:48:19 2016 +0100

    Do not accidentaly override commandline passed CFLAGS.
    
    Signed-off-by: Tomáš Chvátal <tchvatal@suse.com>
    Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/configure.ac b/configure.ac
index 3ba1386..1552c15 100644
--- a/configure.ac
+++ b/configure.ac
@@ -53,7 +53,7 @@ AS_IF([test "x${prefix}" = "xNONE"], [
 # ================
 # Check for cflags
 # ================
-CFLAGS="-D_GNU_SOURCE -Wall -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64"
+CFLAGS="$CFLAGS -D_GNU_SOURCE -Wall -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64"
 AC_ARG_ENABLE([werror],
     [AS_HELP_STRING([--enable-werror], [Treat all warnings as errors, useful for development])],
     [enable_werror="$enableval"],