pgsql: Allow a major PG version psql .psqlrc file to be used if a minor

Allow a major PG version psql .psqlrc file to be used if a minor
matching version file does not exist. This avoids needing to rename
.psqlrc files after minor version upgrades.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/2795592e52c88e510ae4bcbc17b305d6adc0b2b6

Modified Files
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doc/src/sgml/ref/psql-ref.sgml | 6 ++++--
src/bin/psql/startup.c | 19 +++++++++++++------
2 files changed, 17 insertions(+), 8 deletions(-)