Before, make check-world would create a new temporary installation for
each test suite, which is slow and wasteful.  Instead, we now create one
test installation that is used by all test suites that are part of a
make run.

The management of the temporary installation is removed from pg_regress
and handled in the makefiles.  This allows for better control, and
unifies the code with that of test suites not run through pg_regress.

review and msvc support by Michael Paquier <michael.paquier@gmail.com>

more review by Fabien Coelho <coelho@cri.ensmp.fr>