libext2fs: fix crash when ext2fs_mmp_stop() is called before MMP is initialized

The fatal_error() function in e2fsck can call ext2fs_mmp_stop() on a
file system where MMP hasn't yet been initialized.  When that happens,
instead of crashing, have ext2fs_mmp_stop() return success, since mmp
doesn't need to be stopped if it hasn't even been initialized yet.

Addresses-Debian-Bug: #696609
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
1 file changed