pgsql: If we don't have a backup-end-location, don't claim we've reache

If we don't have a backup-end-location, don't claim we've reached it.

This was apparently a typo, which caused recovery to think that it
immediately reached the end of backup, and allowed the database to start
up too early.

Reported by Jeff Janes. Backpatch to 9.2, where this code was introduced.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/ffc3172e4e3caee0327a7e4126b5e7a3c8a1c8cf

Modified Files
--------------
src/backend/access/transam/xlog.c |    2 +-
1 files changed, 1 insertions(+), 1 deletions(-)