With Clang 5.0 the .arch directive is required, otherwise Clang
complains "error: instruction requires: crc".
This was reported in D10499 but not added initially, because clang 3.8
available on a ref machine reported unknown directive. Clang 4.0 allows
but does not require the directive.
Submitted by: andrew
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
available and if that is true make use of them.
Thank you very much to Andrew Turner for providing help and review the patch!
Reviewed by: andrew
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D10499