* eval.c (Fcondition_case): Rearranged for clarity. Don't worry

* eval.c (Fcondition_case): Rearranged for clarity.  Don't worry
	about setting h.poll_suppress_count; it's guaranteed to be the
	same as c.poll_suppress_count.
	(internal_condition_case): Don't worry about
	h.poll_suppress_count.
	(Fsignal): Use h->tag->poll_suppress_count instead of
	h->poll_suppress_count.

	* eval.c (Fsignal): It's okay for the debugger to return to the
	caller if the caller was signalling a quit.

	* eval.c (unbind_catch): Restore the polling suppression count
	here, instead of in Fsignal and Fthrow.
	(Fthrow, Fsignal): Don't restore the polling suppression count here.

	* eval.c (struct catchtag): More documentation.

	* eval.c (entering_debugger): Variable renamed
	when_entered_debugger, and is now a timestamp based on
	num_nonmacro_input_chars.
	(init_eval): Initialize when_entered_debugger, not
	entering_debugger.
	(call_debugger): Set when_entered_debugger to the current value of
	num_nonmacro_input_chars.
	(find_handler_clause): Don't call debugger unless
	num_nonmacro_input_chars is greater than when_entered_debugger;
	that way, we won't call the debugger unless the user has had a
	chance to take control.
	(Fbacktrace): Don't clear entering_debugger here.