Restore cleaning of lib/charset.alias

Even though we now prevent linking of this file into the prefix in
Keg#link, its presence still triggers a "non-lib in lib" warning during
installation. So keep cleaning it, and leave the check in Keg#link so
things that skip_clean 'lib' still won't have it linked.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/cleaner.rb

@@ -78,6 +78,8 @@ class Cleaner
       elsif path.extname == '.la'
         # *.la files are stupid
         path.unlink unless @f.skip_clean? path
+      elsif path == @f.lib+'charset.alias'
+        path.unlink unless @f.skip_clean? path
       elsif not path.symlink?
         clean_file path
       end