re2c: Work around tmpfile() issue on win32.

tmpfile() defaults to C:\, and on Windows 7 can run into permissions issues.
Add workaround implementation from cairo
(http://cgit.freedesktop.org/cairo/commit/?id=4fa46e3caaffb54f4419887418d8d0ea39816092)

See also: http://msdn.microsoft.com/en-us/library/x8x7sakw(v=VS.80).aspx
(community content section)