Add mode where contrib installcheck runs each module in a separately named database.

Normally each module is tested in a database named contrib_regression,
which is dropped and recreated at the beginhning of each pg_regress run.
This new mode, enabled by adding USE_MODULE_DB=1 to the make command
line, runs most modules in a database with the module name embedded in
it.

This will make testing pg_upgrade on clusters with the contrib modules
a lot easier.

Second attempt at this, this time accomodating make versions older
than 3.82.

Still to be done: adapt to the MSVC build system.

Backpatch to 9.0, which is the earliest version it is reasonably
possible to test upgrading from.

contrib/dblink/Makefile

@@ -11,6 +11,9 @@ DATA = dblink--1.1.sql dblink--1.0--1.1.sql dblink--unpackaged--1.0.sql
 
 REGRESS = dblink
 
+# the db name is hard-coded in the tests
+override USE_MODULE_DB =
+
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)

src/Makefile.global.in

@@ -428,6 +428,15 @@ submake-libpgport:
 
 PL_TESTDB = pl_regression
 CONTRIB_TESTDB = contrib_regression
+ifneq ($(MODULE_big),)
+  CONTRIB_TESTDB_MODULE = contrib_regression_$(MODULE_big)
+else 
+  ifneq ($(MODULES),)
+    CONTRIB_TESTDB_MODULE = contrib_regression_$(MODULES)
+  else
+    CONTRIB_TESTDB_MODULE = contrib_regression
+  endif
+endif
 
 ifdef NO_LOCALE
 NOLOCALE += --no-locale

src/makefiles/pgxs.mk

@@ -240,7 +240,11 @@ distclean maintainer-clean: clean
 ifdef REGRESS
 
 # Select database to use for running the tests
-REGRESS_OPTS += --dbname=$(CONTRIB_TESTDB)
+ifneq ($(USE_MODULE_DB),)
+  REGRESS_OPTS += --dbname=$(CONTRIB_TESTDB_MODULE)
+else
+  REGRESS_OPTS += --dbname=$(CONTRIB_TESTDB)
+endif
 
 # where to find psql for running the tests
 PSQLDIR = $(bindir)