Add test_pg_dump to @contrib_excludes

The test_pg_dump extension doesn't have a C component, so we need
to exclude it from the MSVC build system trying to figure out how
to build it.

Also add a "MODULES" line to the Makefile, as test_extensions has.
Might not be necessary, but seems good to keep things consistent.

Lastly, remove the 'installcheck' line from test_pg_dump, as that
was causing redefinition errors, at least on my box.  This also
makes test_pg_dump consistent with how commit_ts is set up.

src/test/modules/test_pg_dump/Makefile

 # src/test/modules/test_rls_hooks/Makefile
 
+MODULE = test_pg_dump
 PGFILEDESC = "test_pg_dump - Test pg_dump with an extension"
 
 EXTENSION = test_pg_dump
@@ -12,9 +13,6 @@ check: prove-check
 prove-check:
 	$(prove_check)
 
-installcheck:
-	$(prove_installcheck)
-
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)

src/tools/msvc/Mkvcbuild.pm

@@ -43,7 +43,7 @@ my $contrib_extrasource = {
 my @contrib_excludes = (
 	'commit_ts',       'hstore_plperl',    'hstore_plpython', 'intagg',
 	'ltree_plpython',  'pgcrypto',         'sepgsql',         'brin',
-	'test_extensions', 'snapshot_too_old');
+	'test_extensions', 'test_pg_dump', 'snapshot_too_old');
 
 # Set of variables for frontend modules
 my $frontend_defines = { 'initdb' => 'FRONTEND' };