[master] 78203c1 Check for -Wfoo rather than -Wno-foo, since gcc ignores the latter

[Tollef Fog Heen]

commit 78203c1cd83377f07e70e6bea125eef67ab19d70
Author: Tollef Fog Heen <tfheen at varnish-software.com>
Date:   Fri Nov 29 13:54:58 2013 +0100

    Check for -Wfoo rather than -Wno-foo, since gcc ignores the latter

diff --git a/configure.ac b/configure.ac
index 10ed5d1..98f7113 100644
--- a/configure.ac
+++ b/configure.ac
@@ -458,10 +458,10 @@ gl_LD_VERSION_SCRIPT
 # failures.
 CFLAGS="${CFLAGS} -Wall -Werror"
 OCFLAGS="${OCFLAGS} -Wall -Werror"
-AX_CHECK_COMPILE_FLAG([-Wno-error=unused-result],
+AX_CHECK_COMPILE_FLAG([-Werror=unused-result],
     [CFLAGS="${CFLAGS} -Wno-error=unused-result"
      OCFLAGS="${OCFLAGS} -Wno-error=unused-result"],
-    [AX_CHECK_COMPILE_FLAG([-Wno-unused-result],
+    [AX_CHECK_COMPILE_FLAG([-Wunused-result],
      [CFLAGS="${CFLAGS} -Wno-unused-result"
       OCFLAGS="${OCFLAGS} -Wno-unused-result"])])