Ruby

file.c: use filesystem encoding

• file.c (rb_realpath_internal): use filesystem encoding if the
  argument is in ASCII encodings.
• win32/file.c (rb_readlink): needs the result encoding.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51738 b2dd03c8-39d4-4d8f-98ff-823fe69b080e