(find_handler_clause): Use maybe_call_debugger.
Call it when the handler says `debug'.
Eliminate DEBUGGER_VALUE_PTR.
(Fsignal): Eliminate debugger_value.
(Qdebug): New variable.
(syms_of_eval): Initialize it.
(xsignal0, xsignal1, xsignal2, xsignal3): New no-return functions.
(signal_error): New no-return function (from xfaces.c).
(Fthrow): Use xsignal2 instead of Fsignal + abort.
(error): Use xsignal1 instead of Fsignal + abort.
(FletX, Flet, grow_specpdl): Use signal_error.
(Feval, Ffuncall, funcall_lambda): Use xsignal1, xsignal2.
* xfaces.c (signal_error): Move to eval.c.
(resolve_face_name): Use xsignal1.
(Feval, Fapply, Ffuncall): Optimize for no function indirection.
Use original function name in all signaled errors.
Simplify Fsignal calls (no return).
(funcall_lambda): Simplify Fsignal calls (no return).
(x_uncatch_errors): Unused count argument deleted.
* xterm.c (x_catch_errors): Don't use record_unwind_protect, since
it can be called in a signal handler.
(x_catch_errors_unwind): Function deleted.
(x_uncatch_errors): Deallocate last x_error_message_stack struct.
(x_check_errors): Call x_uncatch_errors before signalling error.
(x_load_font, x_term_init, XTmouse_position, handle_one_xevent)
(x_connection_closed, x_list_fonts): Use new versions of
x_catch_errors and x_uncatch_errors.
* xselect.c (x_own_selection, x_decline_selection_request)
(x_reply_selection_request, x_get_foreign_selection)
(Fx_get_atom_name, Fx_send_client_event): Likewise.
* xfns.c (x_real_positions, x_set_mouse_color, Fx_focus_frame):
Likewise.
* eval.c (record_unwind_protect): Add an assertion.
to pass Qnil for NOERROR.
* keymap.c (current_minor_maps_error): Remove.
(current_minor_maps): Pass Qt for NOERROR to Findirect_function
instead of using internal_condition_case_1+current_minor_maps_error.
to make space for the debugger, and restore the change afterward.
Bind debug-on-error to nil.
(restore_stack_limits): New subroutine.
(Fsignal): Extend specpdl bound along with eval depth bound,
for calling edebug. Don't do either one, for calling debugger.
(find_handler_clause): Don't bind debug-on-error here.
Don't unbind anything either.
Temporarily advance max_specpdl_size for calling
internal_with_output_to_temp_buffer.
(grow_specpdl): Don't alter max_specpdl_size before signaling an error.
(syms_of_eval) <max-specpdl-size>: Doc fix.
