linux-user: move s390x signal.c parts to s390x directory

No code change, only move code from signal.c to
s390x/signal.c, except adding includes and
exporting setup_frame() and setup_rt_frame().

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180424192635.6027-10-laurent@vivier.eu>
3 files changed