pgsql: Adjust pg_upgrade check for pg_upgrade_support to happen after t

Adjust pg_upgrade check for pg_upgrade_support to happen after the
binary directory has been validated.

Backpatch to 9.1.

Dan McGee

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/c6635bd7ba4618b7d8507c77d2226f889e3d37d9

Modified Files
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contrib/pg_upgrade/check.c | 56 ++++++++++++++++++++++++++++----------
contrib/pg_upgrade/option.c | 45 -------------------------------
contrib/pg_upgrade/pg_upgrade.h | 1 -
3 files changed, 41 insertions(+), 61 deletions(-)