Current implementation uses GetShortPathName and GetLongPathName
to get a normalized path. That approach sometimes fails because
user can disable short path name anytime. This CL provides
an alternative approach suggested by MSDN.

https://msdn.microsoft.com/en-us/library/windows/desktop/aa364989(v=vs.85).aspx

Fixes #13980

Change-Id: Icf4afe4c9c4b507fc110c1483bf8db2c3f606b0a
Reviewed-on: https://go-review.googlesource.com/20860Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>