target-s390: Move facilities bits to env

Rather than simply hard-coding them in STFL instruction.

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Implement STFLE

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Update list of supported facilities

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Implement SAM31 and SAM64

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Implement EPSW

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Fix STIDP

The implementation had been incomplete, as we did not store the
machine type.

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Fix STURA

We were storing 16 bits instead of 32.

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Implement LURA, LURAG, STURG

Signed-off-by: Richard Henderson <rth@twiddle.net>
target-s390: Implement ECAG

Signed-off-by: Richard Henderson <rth@twiddle.net>