* Fix build on FreeBSD

On FreeBSD amd64, both uname -p and uname -m returns amd64 (lowercase).
It seems Windows returns AMD64 (uppercase).

Reference:
[1] https://cmake.org/cmake/help/latest/variable/CMAKE_SYSTEM_PROCESSOR.html
[2] https://cmake.org/cmake/help/latest/variable/CMAKE_HOST_SYSTEM_PROCESSOR.html

* Use MATCHES for multiple values