pgsql: Add basic TAP tests for psql's tab-completion logic.

Add basic TAP tests for psql's tab-completion logic.

Up to now, psql's tab-complete.c has had exactly no regression test
coverage.  This patch is an experimental attempt to add some.

This needs Perl's IO::Pty module, which isn't installed everywhere,
so the test script just skips all tests if that's not present.
There may be other portability gotchas too, so I await buildfarm
results with interest.

So far this just covers a few very basic keyword-completion and
query-driven-completion scenarios, which should be enough to let us
get a feel for whether this is practical at all from a portability
standpoint.  If it is, there's lots more that can be done.

Discussion: https://postgr.es/m/[email protected]

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7c015045b9141cc30272930ea88cfa5df47240b7

Modified Files
--------------
configure                            |   2 +
configure.in                         |   1 +
src/Makefile.global.in               |   1 +
src/bin/psql/.gitignore              |   2 +-
src/bin/psql/Makefile                |  10 +++
src/bin/psql/t/010_tab_completion.pl | 122 +++++++++++++++++++++++++++++++++++
src/test/perl/PostgresNode.pm        |  67 +++++++++++++++++++
7 files changed, 204 insertions(+), 1 deletion(-)