Revert r50867, which added '.PHONY' to the freebsd-releng/Makefile

to ensure the article.html file would always be updated if any of
the dependent releng-*.xml files were updated.

Implement a proper fix to ensure the dependencies are properly
tracked, and the page(s) are rebuilt after an update.

Thank you to wosch@ for providing the correct fix for this.

Submitted by:	wosch
Sponsored by:	The FreeBSD Foundation

en_US.ISO8859-1/articles/freebsd-releng/Makefile

@@ -12,11 +12,14 @@ INSTALL_ONLY_COMPRESSED?=
 
 SRCS=		article.xml
 
+DEPS!= egrep '<!ENTITY release\.[^ ]+ SYSTEM "./releng-[^ ]+\.xml">' \
+	${SRCS} | sed -E 's,.*"./([^"]+)".*,\1,'
+
 CSS_SHEET_ADDITIONS=extra.css
 
 URL_RELPREFIX?=	../../../..
 DOC_PREFIX?=	${.CURDIR}/../../..
 
-all: .PHONY clean
+index.html ${DOC}.html: ${DEPS}
 
 .include "${DOC_PREFIX}/share/mk/doc.project.mk"