In the ufsdirhash_build() failure case for corrupted directories or unreadable blocks, make sure to destroy the mutex we created. Also fix an unrelated typo in a comment.
In the ufsdirhash_build() failure case for corrupted directories
or unreadable blocks, make sure to destroy the mutex we created.
Also fix an unrelated typo in a comment.

Found by:	Peter Holm's stress tests
Reviewed by:	dwmalone
MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase