Rewriting the test of pg_upgrade as a TAP test

Hi all,

The $subject has been mentioned a couple of times already, the last
one being here:
https://www.postgresql.org/message-id/20170401072814.GA2528448@tornado.leadboat.com

The code tree has to maintain now two set of scripts for the same
test: test.sh for all *nix platforms, and vcregress.pl for MSVC.
Attached is a patch to remove that and replace the existing test by a
TAP test. The size of the patch speaks by itself:
6 files changed, 98 insertions(+), 389 deletions(-)

I had for some time a WIP patch on which dust has accumulated, so
attached is a more polished version. In more details, here is what
happens:
- test.sh is removed.
- vcregress.pl loses upgradecheck.
- The new test is added. In the case of MSVC this is now part of bincheck.
Patch has been tested on macos and Windows.

I am parking that in the next commit fest.

Regards,
--
Michael