userfaultfd: selftest: don't error out if pthread_mutex_t isn't identical

On ppc big endian this check fails, the mutex doesn't necessarily need
to be identical for all pages after pthread_mutex_lock/unlock cycles.
The count verification (outside of the pthread_mutex_t structure)
suffices and that is retained.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>