Avoid extra "skipping" messages from VACUUM/ANALYZE

Right now, if an unprivileged user issues VACUUM/ANALYZE (without
specifying a table), it will emit messages for each relation that it
skips, including indexes, views, and other objects that can't be a
direct target of VACUUM/ANALYZE anyway. Attached patch causes it to
check the type of object first, and then check privileges second.

Found while reviewing the MAINTAIN privilege patch. Implemented with
his suggested fix. I intend to commit soon.


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Jeff Davis
PostgreSQL Contributor Team - AWS