pgsql: Silence compiler warning about undefined function when compiling

Silence compiler warning about undefined function when compiling without
assertions.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/baabf05196922164db80bdc45fd0660c8700f1f7

Modified Files
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src/backend/replication/syncrep.c |    2 ++
1 files changed, 2 insertions(+), 0 deletions(-)