configure: fix return value from check_header

Originally committed as revision 17695 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/configure b/configure
index 813a333..281ce24 100755 (executable)
--- a/configure
+++ b/configure
@@ -574,7 +574,8 @@ check_header(){
     log check_header "$@"
     header=$1
     shift
-    check_cpp "$@" <<EOF && enable_safe $header || disable_safe $header
+    disable_safe $header
+    check_cpp "$@" <<EOF && enable_safe $header
 #include <$header>
 int x;
 EOF