Rework spill LAP mechanism in preparation of compiling lambdas.

Rework spill LAP mechanism in preparation of compiling lambdas.

	* lisp/emacs-lisp/comp.el (comp-spill-lap-function): No need anymore
	to have `byte-native-compiling' bound to free-func.
	(comp-spill-lap-function): Make use of `byte-to-native-lap-h' and
	clean-up.
	(comp-spill-lap-function): Likewise.

	* lisp/emacs-lisp/bytecomp.el (byte-to-native-function): Add lap slot.
	(byte-to-native-lap): Rename into byte-to-native-lap-h.
	(byte-compile-lapcode): Spill lap after having int assembled and
	store it into `byte-to-native-lap-h'.
	(byte-compile-not-top-level): Remove.
	(byte-compile-file-form-defmumble): Fill directly lap slot.
	(byte-compile-lambda): Remove `byte-compile-not-top-level'.
	(byte-compile-out-toplevel): Restore original code.
	(byte-compile-form): Remove `byte-compile-not-top-level'.
	(byte-compile-function-form): Likewise.
	(byte-compile-flush-pending): No need anymore to set
	`byte-compile-current-form' so restore orignal code.