Support vpath builds in TAP tests

src/Makefile.global.in

@@ -301,13 +301,13 @@ PG_PROVE_FLAGS = --ext='.pl' -I $(top_srcdir)/src/test/perl/
 PROVE_FLAGS = --verbose
 
 define prove_installcheck
-PATH="$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
+cd $(srcdir) && TESTDIR='$(CURDIR)' PATH="$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
 endef
 
 define prove_check
 $(MKDIR_P) tmp_check/log
 $(MAKE) -C $(top_builddir) DESTDIR=$(CURDIR)/tmp_check/install install >$(CURDIR)/tmp_check/log/install.log 2>&1
-PATH="$(CURDIR)/tmp_check/install$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
+cd $(srcdir) && TESTDIR='$(CURDIR)' PATH="$(CURDIR)/tmp_check/install$(bindir):$$PATH" PGPORT='6$(DEF_PGPORT)' $(PROVE) $(PG_PROVE_FLAGS) $(PROVE_FLAGS)
 endef
 
 # Installation.

src/test/perl/TestLib.pm

@@ -62,7 +62,7 @@ $ENV{PGPORT} = int($ENV{PGPORT}) % 65536;
 
 sub tempdir
 {
-	return File::Temp::tempdir('testXXXX', DIR => cwd(), CLEANUP => 1);
+	return File::Temp::tempdir('tmp_testXXXX', DIR => $ENV{TESTDIR} || cwd(), CLEANUP => 1);
 }
 
 my ($test_server_datadir, $test_server_logfile);