simplify check_lib

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@8030 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -443,11 +443,7 @@ check_lib(){
     header="$1"
     func="$2"
     shift 2
-    temp_extralibs "$@"
-    check_header $header && check_func $func && add_extralibs "$@"
-    err=$?
-    restore_flags
-    return $err
+    check_header $header && check_func $func "$@" && add_extralibs "$@"
 }
 
 check_exec(){