--- configure.orig	2013-02-15 17:08:00.000000000 +0900
+++ configure	2013-02-20 00:08:29.000000000 +0900
@@ -17989,8 +17989,8 @@
 fi
 
 if test -n "$GCC"; then
-   CFLAGS="-O3 -Wall "
-   CXXFLAGS="-O3 -Wall "
+   CFLAGS="$CFLAGS -Wall "
+   CXXFLAGS="$CXXFLAGS -Wall "
 fi