* op_utils.c (do_syscall): Rewrite to use common/syscall.c.
(syscall_read_mem, syscall_write_mem): New functions for syscall
callbacks.
* mn10300_sim.h: Add prototypes for syscall_read_mem and
syscall_write_mem.
* mn10300.igen: Change C++ style comments to C style comments.
Check for divide by zero in div and divu ops.