[PATCH] Move generic isPrint and columnWidth implementations to a separate header/source to allow using both generic and system-dependent versions on win32.

[Alexander Kornienko]

  > Windows version of clang-format.

  Let me clarify this a bit: we'd like windows build of clang-format to format files in the same way as it does on other platforms, so we need access to the platform-independent implementation of Unicode-related functions.

  We'll definitely need to address Unicode-related problems with i/o in windows build, but this is a different story (at least, clang-format's main use case doesn't involve printing source code to the console).

http://llvm-reviews.chandlerc.com/D1559