* win32/Makefile.sub: r41163 changed win32/win32.c and configure.in
  but it didn't treat about mswin32/mswin64, so fix it.
  NOTE: this needs a review by usa whether additional condition is
  required or not.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41173 b2dd03c8-39d4-4d8f-98ff-823fe69b080e