* config/h8300/h8300-protos.h (function_arg): Delete.
* config/h8300/h8300.h (FUNCTION_ARG, FUNCTION_ARG_ADVANCE): Delete.
* config/h8300/h8300.c (function_arg): Rename to...
(h8300_function_arg): ...this. Make static. Take a const_tree and
a bool.
(h8300_function_arg_advance): New function.
(TARGET_FUNCTION_ARG, TARGET_FUNCTION_ARG_ADVANCE): Define.