fs/namespace.c: bury long-dead define

MNT_WRITER_UNDERFLOW_LIMIT has been missed 4 years ago when it became unused.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-09-28 12:54:06 -04:00
commit 085e83ff0c