suppress msys2 pathname conversion
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54211 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
suppress msys2 pathname conversion
long option.
conversions by msys2. [ruby-dev:49525] [Bug #12199]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54211 b2dd03c8-39d4-4d8f-98ff-823fe69b080e