See the comment in win32/Makefile.sub.
Not only .pch, but also .obj needs to be installed and used on runtime.

.gitignore: ignore .pch that will be built by this.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64188 b2dd03c8-39d4-4d8f-98ff-823fe69b080e