dir.c: fallback to ASCII-8BIT

* dir.c (push_glob): fallback to ASCII-8BIT for the case non-ascii
  path name exists.  failed with LANG=C, on MacOS X which has a
  localized symlink on the root directory.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44834 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

dir.c

@@ -1748,6 +1748,7 @@ push_glob(VALUE ary, VALUE str, int flags)
     rb_encoding *enc = rb_enc_get(str);
 
     if (enc == rb_usascii_encoding()) enc = rb_filesystem_encoding();
+    if (enc == rb_usascii_encoding()) enc = rb_ascii8bit_encoding();
     args.func = push_pattern;
     args.value = ary;
     args.enc = enc;