Bug 504239. Remove useless chunk of barely-used script. r=ted

build/autoconf/clean-config.sh

@@ -55,11 +55,6 @@ if [ ! -f configure.in ]; then
   exit 1
 fi
 
-if [ -f mailnews/makefiles ]; then
-  MOZ_MAIL_NEWS=1
-  export MOZ_MAIL_NEWS
-fi
-
 . allmakefiles.sh
 
 rm -fr $MAKEFILES \