allow man(1) to find the ports/infrastructure manpages by default.

ok dcoppa@ phessler@ jasper@ landry@ rpointel@ giovanni@ ajacoutot@ henning@
no problem jmc@

src/etc/man.conf

@@ -1,4 +1,4 @@
-#	$OpenBSD: man.conf,v 1.16 2010/10/19 20:05:52 schwarze Exp $
+#	$OpenBSD: man.conf,v 1.17 2011/04/11 14:45:41 sthen Exp $
 
 # Sheer, raging paranoia...
 _version	BSD.2
@@ -31,7 +31,7 @@ _build		.tbl.gz		/usr/bin/gzcat %s | /usr/bin/mandoc
 # directory with all of the subdirectories listed for the keyword _subdir.
 
 # default
-_default	/usr/{share,X11R6,local}/man/
+_default	/usr/{share,X11R6,local,ports/infrastructure}/man/
 
 # Other sections that represent complete man subdirectories.
 X11		/usr/X11R6/man/