pgsql: Add basic pg_dumpall/pg_restore TAP tests

Add basic pg_dumpall/pg_restore TAP tests

For reasons unknown, pg_dumpall and pg_restore managed to escape the
basic set of TAP tests that were added for pg_dump in 6bd356c3, so
let's get them added now. A few minor adjustments are also made to the
dump/restore tests to improve code coverage for pg_restore/pg_dumpall.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/9b815a8ff227e62442259e0fbabc5cf37e433df9

Modified Files
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src/bin/pg_dump/t/001_basic.pl | 61 +++++++++++++++++++++++++++++++++++++++-
src/bin/pg_dump/t/002_pg_dump.pl | 8 +++---
2 files changed, 64 insertions(+), 5 deletions(-)