s390x-linux-user now also uses GETPC. Instead of adding it to the list of
targets which use GETPC, the macro is now defined unconditionally.

This avoids future build regressions like this one:

  CC    s390x-linux-user/target-s390x/int_helper.o
cc1: warnings being treated as errors
qemu/target-s390x/int_helper.c: In function ‘helper_divs32’:
qemu/target-s390x/int_helper.c:47: error: implicit declaration of function ‘GETPC’
qemu/target-s390x/int_helper.c:47: error: nested extern declaration of ‘GETPC’

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>