pgsql: Release proclock immediately in RemoveFromWaitQueue() if it

Log Message:
-----------
Release proclock immediately in RemoveFromWaitQueue() if it represents
no held locks.  This maintains the invariant that proclocks are present
only for procs that are holding or awaiting a lock; when this is not
true, LockRelease will fail.  Per report from Stephen Clouse.

Tags:
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REL8_0_STABLE

Modified Files:
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    pgsql/src/backend/storage/lmgr:
        lock.c (r1.145 -> r1.145.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lock.c.diff?r1=1.145&r2=1.145.4.1)