path/filepath: in Rel use case-insensitive comparison on Windows
Compare basepath and targetpath using strings.EqualFold. The absence
of this on Windows causes an unterminating condition in `for` statement
later in the function.
Fixes #13258
Change-Id: Ib5a0caba864ee425dc75ece47b9cf6fb626f47f1
Reviewed-on: https://go-review.googlesource.com/16857
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Alex Brainman <alex.brainman@gmail.com>