Revert "Fix url_fopen() flag values."

No longer needed after martins change to the values.
Though this would have been nicer ABI wise but iam too lazy to maintain this difference

This reverts commit 183401b924.

libavformat/aviobuf.c

@@ -374,7 +374,7 @@ void put_nbyte(AVIOContext *s, int b, int count)
 
 int url_fopen(AVIOContext **s, const char *filename, int flags)
 {
-    return avio_open(s, filename, flags+1);
+    return avio_open(s, filename, flags);
 }
 int url_fclose(AVIOContext *s)
 {