mirror: netcologne is no longer available

mk/mirrors.mk

@@ -28,7 +28,6 @@ MASTER_SITE_GNU?=	\
 	http://ftp.gnu.org/gnu/ \
 
 MASTER_SITE_SOURCEFORGE?=	\
-	http://netcologne.dl.sourceforge.net/sourceforge/ \
 	http://nchc.dl.sourceforge.net/sourceforge/ \
 	http://kent.dl.sourceforge.net/sourceforge/ \
 	http://ufpr.dl.sourceforge.net/sourceforge/ \