Need -I. to build outside source tree.

contrib/tsearch/Makefile

-# $Header: /cvsroot/pgsql/contrib/tsearch/Attic/Makefile,v 1.2 2002/11/01 22:52:33 tgl Exp $
+# $Header: /cvsroot/pgsql/contrib/tsearch/Attic/Makefile,v 1.3 2002/11/01 23:23:29 tgl Exp $
 
 subdir = contrib/tsearch
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
 
+override CPPFLAGS := -I. $(CPPFLAGS)
+
 MODULE_big = tsearch
 OBJS = crc32.o morph.o txtidx.o query.o gistidx.o rewrite.o