not in the same drive.
* ext/extmk.rb: ditto.
* win32/Makefile.sub, win32/README.win32, win32/configure.bat,
win32/setup.mak: new configure scheme. use ``configure --prefix=dir''
instead of ``nmake DESTDIR=dir install''.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@5336 b2dd03c8-39d4-4d8f-98ff-823fe69b080e