pgsql: Throw nice error if server is too old to support psql's \ef or \

Throw nice error if server is too old to support psql's \ef or \sf command.

Previously, you'd get "function pg_catalog.pg_get_functiondef(integer) does
not exist", which is at best rather unprofessional-looking.  Back-patch
to 8.4 where \ef was introduced.

Josh Kupershmidt

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/c49130ade4dac5d8dff724cf15b0f0cdb9cf7d24

Modified Files
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src/bin/psql/command.c |    8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)