Update openstack/common/lockutils

The following commits are in this update:

79e6bc6 fix lockutils.lock() to make it thread-safe
ace5120 Add main() to lockutils that creates temp dir for locks
537d8e2 Allow lockutils to get lock_path conf from envvar
371fa42 Move LockFixture into a fixtures module
d498c42 Fix to properly log when we release a semaphore

Change-Id: Iefe5f90b3886c58736bdb27e9019bc19a8e49179
Merge "Update openstack/common/lockutils"