pgsql: In pg_upgrade, try to convert the locale names to canonical form

In pg_upgrade, try to convert the locale names to canonical form before
comparison; also report the old/new values if they don't match.

Backpatch to 9.2.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/b61837a49f4b4ea12e7ced8e3039ae98908c7c0b

Modified Files
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contrib/pg_upgrade/check.c | 72 ++++++++++++++++++++++++++++++++++++++++----
1 files changed, 66 insertions(+), 6 deletions(-)