vector address according to cpu mode.
(interrupts_initialize): Move reset portion to the above.
(interrupt_names): New table to give a name to interrupts.
(idefs): Handle pulse accumulator interrupts.
(interrupts_info): Print the interrupt history.
(interrupt_option_handler): New function.
(interrupt_options): New table of options.
(interrupts_update_pending): Keep track of when interrupts are
raised and implement breakpoint-on-raise-interrupt.
(interrupts_process): Keep track of when interrupts are taken
and implement breakpoint-on-interrupt.
* interrupts.h (struct interrupt_history): Define.
(struct interrupt): Keep track of the interrupt history.
(interrupts_reset): Declare.
(interrupts_initialize): Update prototype.
* m68hc11_sim.c (cpu_reset): Reset interrupts.
(cpu_initialize): Cleanup.
pending interrupts.
* interrupts.c (interrupts_process): Keep track of the last number
of masked insn cycles.
(interrupts_initialize): Clear last number of masked insn cycles.
(interrupts_info): Report them.
(interrupts_update_pending): Compute clear and set masks of
interrupts and clear the interrupt bits before setting them
(due to SCI interrupt sharing).
* interrupts.h (struct interrupts): New members last_mask_cycles
and xirq_last_mask_cycles.
