Have man page generation work on VPATH builds too.

doc/src/sgml/Makefile

@@ -2,7 +2,7 @@
 #
 # PostgreSQL documentation makefile
 #
-# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.106 2008/06/10 00:19:32 alvherre Exp $
+# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.107 2008/08/25 15:34:05 alvherre Exp $
 #
 #----------------------------------------------------------------------------
 
@@ -66,9 +66,9 @@ DEFAULTSECTION = $(sqlmansect_dummy)
 fix_man_xrefs = $(PERL) -npi -e 's{\[XRef to GUC-([A-Z0-9-]*)\]}{($$l = $$1) =~ tr/A-Z-/a-z_/, $$l}ge || s{\[XRef to [A-Z0-9-]*\]}{in the documentation}g'
 
 man: postgres.sgml $(ALLSGML)
-	$(NSGMLS) $(NSGMLS_FLAGS) $< | $(SGMLSPL) $(D2MSCRIPT) --lowercase --section $(DEFAULTSECTION) --date "`date '+%Y-%m-%d'`"
+	$(NSGMLS) $(NSGMLS_FLAGS) $(SGMLINCLUDE) $< | $(SGMLSPL) $(D2MSCRIPT) --lowercase --section $(DEFAULTSECTION) --date "`date '+%Y-%m-%d'`"
 # One more time, to resolve cross-references
-	$(NSGMLS) $(NSGMLS_FLAGS) $< | $(SGMLSPL) $(D2MSCRIPT) --lowercase --section $(DEFAULTSECTION) --date "`date '+%Y-%m-%d'`"
+	$(NSGMLS) $(NSGMLS_FLAGS) $(SGMLINCLUDE) $< | $(SGMLSPL) $(D2MSCRIPT) --lowercase --section $(DEFAULTSECTION) --date "`date '+%Y-%m-%d'`"
 	$(fix_man_xrefs) *.1 *.$(DEFAULTSECTION)
 	$(mkinstalldirs) man1 man$(DEFAULTSECTION)
 	mv *.1 man1/