enable certain TAP tests for MSVC builds

Certain TAP tests rely on settings that the Make files provide for them.
However vcregress.pl doesn't provide those settings. This patch remedies
that, and I propose to apply it shortly (when we have a fix for the SSL
tests that I will write about separately) and backpatch it appropriately.


cheers


andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com