Upgrade pgTAP to v0.94.0.
Also install pg_prove.
No symbol version of cpanminus.
Removed column alignment and inlined version in the URL.
Install CPAN prereqs as resources.

Rather than using cpanm. Idea borrowed from `clipsafe.rb`, with thanks to
@mikemcquaid for the pointer.
Must make before install.
Install Perl modules in prefix.

So that the apps (prove, pg_prove, pg_tapgen) will be properly linked.
Find out what pg_config we're using.
Put man pages where Homebrew wants them.
Find pg_config without reference to the version.
Depend on 'postgresql', not :postgresql.

Because the latter allows the system postgres, but we cannot install into its directories.
Make sure modules can find dependencies as they build.

The reason for setting $PERL5LIB is so that, when
TAP::Parser::SourceHandler::pgTAP is built, it can find Test::Harness, which
will have been built, but not yet symlinked.