Build and install diff.info..

As Bruce said, this is a little bogus, it'd be nice if bsd.prog.mk knew
about .texi in the same way as it does man pages..

Submitted by: bde

gnu/usr.bin/diff/Makefile

@@ -1,9 +1,11 @@
-
+# $Id$
 PROG=	diff
 SRCS=	diff.c analyze.c io.c context.c ed.c normal.c ifdef.c util.c dir.c \
 	version.c getopt.c getopt1.c side.c cmpbuf.c
 CFLAGS+=-DHAVE_CONFIG_H
 
+SUBDIR+= doc
+
 DPADD+= ${LIBGNUREGEX}
 LDADD+= -lgnuregex
 

gnu/usr.bin/diff/doc/Makefile

@@ -0,0 +1,7 @@
+# $Id$
+
+INFO = diff
+
+.PATH: ${.CURDIR}/..
+
+.include <bsd.info.mk>