Improve speed of make check-world

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>

src/pl/plperl/GNUmakefile

@@ -69,8 +69,6 @@ ifeq ($(shell $(PERL) -V:usemultiplicity), usemultiplicity='define';)
 	REGRESS += plperl_plperlu
 endif
 endif
-# where to find psql for running the tests
-PSQLDIR = $(bindir)
 
 # where to find xsubpp for building XS.
 XSUBPPDIR = $(shell $(PERL) -e 'use List::Util qw(first); print first { -r "$$_/ExtUtils/xsubpp" } @INC')

src/pl/plpython/Makefile

@@ -115,9 +115,6 @@ REGRESS = \
 
 REGRESS_PLPYTHON3_MANGLE := $(REGRESS)
 
-# where to find psql for running the tests
-PSQLDIR = $(bindir)
-
 include $(top_srcdir)/src/Makefile.shlib
 
 all: all-lib

src/pl/tcl/Makefile

@@ -45,8 +45,6 @@ DATA = pltcl.control pltcl--1.0.sql pltcl--unpackaged--1.0.sql \
 
 REGRESS_OPTS = --dbname=$(PL_TESTDB) --load-extension=pltcl
 REGRESS = pltcl_setup pltcl_queries
-# where to find psql for running the tests
-PSQLDIR = $(bindir)
 
 # Tcl on win32 ships with import libraries only for Microsoft Visual C++,
 # which are not compatible with mingw gcc. Therefore we need to build a