Partial fix for contrib vpath breakage.

src/makefiles/pgxs.mk

 # PGXS: PostgreSQL extensions makefile
 
-# $PostgreSQL: pgsql/src/makefiles/pgxs.mk,v 1.13 2008/10/01 22:38:56 petere Exp $ 
+# $PostgreSQL: pgsql/src/makefiles/pgxs.mk,v 1.14 2008/10/02 12:25:25 tgl Exp $ 
 
 # This file contains generic rules to build many kinds of simple
 # extension modules.  You only need to set a few variables and include
@@ -240,7 +240,7 @@ endif
 
 # against installed postmaster
 installcheck: submake
-	$(top_builddir)/src/test/regress/pg_regress --psqldir=$(PSQLDIR) $(REGRESS_OPTS) $(REGRESS)
+	$(top_builddir)/src/test/regress/pg_regress --inputdir=$(srcdir) --psqldir=$(PSQLDIR) $(REGRESS_OPTS) $(REGRESS)
 
 # in-tree test doesn't work yet (no way to install my shared library)
 #check: all submake