target/s390x: Rework program_interrupt() and related functions

target/s390x: Rework program_interrupt() and related functions

misc_helper.c won't be compiled with --disable-tcg anymore, but we
still need the program_interrupt() function in that case. Move it
to interrupt.c instead, and refactor it to re-use the code from
trigger_pgm_exception() (for TCG) and enter_pgmcheck() (for KVM,
which now got renamed to kvm_s390_program_interrupt() for
clarity).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1500886370-14572-4-git-send-email-thuth@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>