CI: cross-compile: Allow to set CPU capabilities

CI: cross-compile: Allow to set CPU capabilities

The cross-compile CI tests use cross-compilers for building
and QEMU for testing. This implies that testing of ISA extension
for HW accelerated cryptographic calculations is undefined
(it depends on arch-specific QEMU defaults and arch-specific
detection mechanisms in OpenSSL).

Let's add a mechanism to set two environment variables, that allow
to control the ISA extensions:
* QEMU_CPU: used by QEMU to specify CPU capabilities of the emulation
* OPENSSL_*: used by OpenSSL (on some architectures) to enable ISA
  extensions.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20107)