pgsql: Print WAL position correctly in pg_rewind error message.

Print WAL position correctly in pg_rewind error message.

This has been wrong ever since pg_rewind was added. The if-branch just
above this, where we print the same error with an extra message supplied
by XLogReadRecord() got this right, but the variable name was wrong in the
else-branch. As a consequence, the error printed the WAL position as
0/0 if there was an error reading a WAL file.

Backpatch to 9.5, where pg_rewind was added.

Branch
------
REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/ee3f036861228f3d85cd9cbb8d158f7209770ccd

Modified Files
--------------
src/bin/pg_rewind/parsexlog.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)