Add DOCSUPFILE, like PORTSSUPFILE. (ie 'make update' in /usr/doc)

PR:		docs/15439
Submitted by:	Christian Weisgerber <naddy@mips.rhein-neckar.de>
Obtained from:	ports/Makefile

Makefile

@@ -1,4 +1,4 @@
-# $FreeBSD: doc/Makefile,v 1.15 1999/09/06 06:52:34 peter Exp $
+# $FreeBSD: doc/Makefile,v 1.16 1999/10/13 00:19:43 phantom Exp $
 #
 # The user can override the default list of languages to build and install
 # with the DOC_LANG variable.
@@ -14,4 +14,24 @@ SUBDIR+=	zh_TW.Big5
 .endif
 
 DOC_PREFIX?=   ${.CURDIR}
+
+update:
+.if defined(SUP_UPDATE)
+.if !defined(DOCSUPFILE)
+	@echo "Error: Please define DOCSUPFILE before doing make update."
+	@exit 1
+.endif
+	@echo "--------------------------------------------------------------"
+	@echo ">>> Running ${SUP}"
+	@echo "--------------------------------------------------------------"
+	@${SUP} ${SUPFLAGS} ${DOCSUPFILE}
+.elif defined(CVS_UPDATE)
+	@echo "--------------------------------------------------------------"
+	@echo ">>> Updating ${.CURDIR} from cvs repository" ${CVSROOT}
+	@echo "--------------------------------------------------------------"
+	cd ${.CURDIR}; cvs -q update -P -d
+.else
+	@echo "Error: Please define either SUP_UPDATE or CVS_UPDATE first."
+.endif
+
 .include "${DOC_PREFIX}/share/mk/doc.subdir.mk"