pgsql: Fix oversight in RelFileNodeBackend patch:

Log Message:
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Fix oversight in RelFileNodeBackend patch: CreateFakeRelcacheEntry needs to
initialize the rd_backend field of a fake Relation entry correctly.
Fortunately, that is easy, since only non-temp relations should ever be
mentioned in the WAL stream.

Modified Files:
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pgsql/src/backend/access/transam:
xlogutils.c (r1.72 -> r1.73)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlogutils.c?r1=1.72&r2=1.73)