* config/h8300/h8300-protos.h: Add a prototype for
compute_a_shift_cc.
* config/h8300/h8300.c (shift_one): Update the CC status.
(shift_two): Likewise.
(output_a_shift_cc): Set cc_inline and cc_special.
(compute_a_shift_cc): New.
* config/h8300/h8300.md (shift insns): Use compute_a_shift_cc.