OpenVMS for x86_64 is currently out on a field test. Building
programs for it is currently done with cross compilation on Itanium.
The cross compilation tools are made available by running a script,
which makes cross-compilation variants of most commands available, and
adds the cross-compilation C compiler XCC.
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16498)
