OpenSSL::config: determine the MSVC target architecture by asking cl
Since cl knows what architecture it builds fore, all depending on what
the user set up, it makes sense to ask it, and use that result primarly,
and only use the POSIX::uname() MACHINE value as a fallback.
Also, this does indeed determine if cl is present or not.
We drop the explicit names in .github/workflows/windows.yml as proof
of concept.
Fixes #19281
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19285)
(cherry picked from commit
0747f94b5f7b7f07f21384507ba1adaea6f99e88)