s390x: Fix s390x_shake_squeeze() when MSA 12 is available

On the first squeeze call, when finishing the absorb process, also set
the NIP flag, if we are still in XOF_STATE_INIT state. When MSA 12 is
available, the state buffer A has not been zeroed during initialization,
thus we must also pass the NIP flag here. This situation can happen
when a squeeze is performed without a preceding absorb (i.e. a SHAKE
of the empty message).

Add a test that performs a squeeze without a preceding absorb and check
if the result is correct.

Fixes: https://github.com/openssl/openssl/commit/25f5d7b85f6657cd2f9f1ab7ae87f319d9bafe54



Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>

Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25388)