struct.c: not_a_member message

* struct.c (not_a_member): extract name error and use same error
  messages.  based on the patch by Marcus Stollsteimer <sto.mar AT
  web.de> at [ruby-core:61721].  [Bug #9684]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45462 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
struct.c: encoding of member name

* struct.c (not_a_member): preserve encoding of member name in
  error messages.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45463 b2dd03c8-39d4-4d8f-98ff-823fe69b080e