pgsql: Fix build with LWLOCK_STATS or dtrace.

Fix build with LWLOCK_STATS or dtrace.

Also fix the name of the dtrace probe for LWLockAcquireOrWait(). The
function was renamed from LWLockWaitUntilFree to LWLockAqcuireOrWait, but
the dtrace probe was neglected.

Pointed out by Andres Freund and the buildfarm.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/dea6ed2c980286e89caf4166ad329f506abbff29

Modified Files
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src/backend/storage/lmgr/lwlock.c |   19 ++++++++++++++-----
src/backend/utils/probes.d        |    4 ++--
2 files changed, 16 insertions(+), 7 deletions(-)