s390x/tcg: Implement LOAD COUNT TO BLOCK BOUNDARY

s390x/tcg: Implement LOAD COUNT TO BLOCK BOUNDARY

Use a new CC helper to calculate the CC lazily if needed. While the
PoP mentions that "A 32-bit unsigned binary integer" is placed into the
first operand, there is no word telling that the other 32 bits (high
part) are left untouched. Maybe the other 32-bit are unpredictable.
So store 64 bit for now.

Bit magic courtesy of Richard.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190225200318.16102-8-david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>