win: handle file paths in uv_fs_statfs()
win: handle file paths in uv_fs_statfs()

GetDiskFreeSpaceW() doesn't handle regular file paths well.
This commit switches to using GetFullPathNameW().

Fixes: https://github.com/libuv/libuv/pull/2683
Refs: https://github.com/libuv/libuv/pull/2691
PR-URL: https://github.com/libuv/libuv/pull/2695
Reviewed-By: Colin Ihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>
Reviewed-By: Jameson Nash <99e7f19e9f64df56d4e81dc00b8566e722cdd766@gmail.com>

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