s390: fix build on 32-bit hosts

Fixes build on i686:

gcc/config/s390/s390.cc: In function 'bool s390_rtx_costs(rtx, machine_mode, int, int, int*, bool)':
gcc/config/s390/s390.cc:3728:63: error: cannot convert 'long int*' to 'long long int*'

gcc/ChangeLog:

	* config/s390/s390.cc (s390_rtx_costs): Use proper type as
	  argument.