pgsql: psql: Add more constraint completion

psql: Add more constraint completion

- ALTER DOMAIN ... DROP/RENAME/VALIDATE CONSTRAINT
- ALTER TABLE ... RENAME/VALIDATE CONSTRAINT
- COMMENT ON CONSTRAINT
- SET CONSTRAINTS

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/05cf0ea8d1c94260cd11811b646ef7b16c148719

Modified Files
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src/bin/psql/tab-complete.c | 88 ++++++++++++++++++++++++++++++++++++++++--
1 files changed, 83 insertions(+), 5 deletions(-)