Workaround needed for windows-rs targets

[gelvinp]

None of the windows-rs targets have license files in the crate source, instead there is a license file in the top level of the git repo.

As seen here:
https://github.com/microsoft/windows-rs
there are both MIT and Apache-2.0 licenses available, but none of the crates in the targets directory have license files, giving the generated license file the default MIT license without the correct copyright info for these targets (e.g. windows_x86_64_msvc)

The workaround I'm using is to set the clarification path to ../windows-sys-0.42.0/license-mit which is just escaping to another crate from this same repo which does have a license file and is checksum identical to the one at the root of the repo. I don't know why this crate has a copy of the license and none of the targets do but whatever works I guess.