Allow per function speed declaration

Allow per function speed declaration

	* src/comp.c (COMP_SPEED): Rename.
	(comp_t): Add 'func_speed' field.
	(emit_mvar_lval, compile_function): Update for per function speed.
	(Fcomp__compile_ctxt_to_file): COMP_SPEED renamed.

	* lisp/emacs-lisp/comp.el (comp-speed): Doc update.
	(comp-func): New 'speed' slot.
	(comp-spill-speed): New function.
	(comp-spill-lap-function, comp-intern-func-in-ctxt): Fill 'speed'
	slot.
	(comp-spill-lap-function): Gate -1 speed functions for native
	compilation and emit bytecode instead.
	(comp-spill-lap): Close over `byte-to-native-plist-environment'.
	(comp-latch-make-fill): Update for per function speed.
	(comp-limplify-top-level): Fill speed.
	(comp-propagate1, comp-call-optim-form-call, comp-call-optim)
	(comp-dead-code, comp-tco, comp-remove-type-hints): Update for per
	function speed.