[CMake] Explicitly specify paths to libc++abi in CrossWinToARMLinux.cmake

Summary:
D69169, which was necessary for running libc++ tests on remote host, got reverted. I couldn't think of a less invasive way to achieve this behavior but specify libc++abi paths in our cache file.

Reviewers: vvereschaka, aorlov, andreil99, EricWF

Reviewed By: vvereschaka

Subscribers: mgorny, kristof.beyls, ldionne, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D74347