Given load loads automatically a .eln in place of a .elc we need a way
to force the .elc load in the case we really want it.

	* src/lread.c (syms_of_lread): Define `load-no-native'.
	(maybe_swap_for_eln): Make use of.

	* lisp/emacs-lisp/bytecomp.el (byte-compile-file): Do not crash if
	native compiling we have no permission to create the .elc
	file.  We are not creating it.

This is needed for installed instances compiled with NATIVE_FAST_BOOT

	* src/comp.c (maybe_defer_native_compilation): Search for .el.gz
	too as a source if the .el is not found.
	(Fcomp_el_to_eln_filename): Remove the .gz in case to
	generate the hash.

	* lisp/emacs-lisp/comp.el (comp-valid-source-re): New defconst.
	(comp-run-async-workers, native-compile-async): Make use of
	`comp-valid-source-re'.

	* src/comp.h (fixup_eln_load_path): New extern.

	* src/comp.c (fixup_eln_load_path): New function.

	* src/pdumper.c (dump_do_dump_relocation): Update to make use of
	'fixup_eln_load_path'.

	* lisp/loadup.el: Update to store in the compilation unit the
	correct eln-cache installed path. Rename --lisp-dest -> --eln-dest
	and.

	* Makefile.in: Pass the eln destination directory to
	src/Makefile. Rename LISP_DESTDIR -> ELN_DESTDIR.
	(ELN_DESTDIR): Define.
	(install-eln): New target.
	(install): Add install-eln as prerequisite.

	* src/Makefile.in: Rename --lisp-dest -> --eln-dest and
	LISP_DESTDIR -> ELN_DESTDIR.

	* lisp/emacs-lisp/comp.el (comp-run-async-workers): Always compile
	if load is set.

	* lisp/emacs-lisp/comp.el (native-compile-async): Call
	make-directory if necessary.

Prevent autoload to kicks in while running `native-compile-async'.
Autoload cannot be used safely by functions serving deferred
compilation as a circular load can be triggered if the dependency is
not native compiled already.

	* lisp/emacs-lisp/comp.el (warnings): Add require.

	* Makefile.in (clean): Remove 'eln-cache' folder.

	* lisp/Makefile.in (.SUFFIXES): Remove .eln.
	(native-compile-clean): Target remove.
	(compile-always, bootstrap-clean): Remove 'native-compile-clean'
	prerequisite.

	* src/Makefile.in (%.eln): Remove rule.

	* src/comp.c (comp_deferred_compilation): Doc update and set it to
	true by default.

	* lisp/emacs-lisp/comp.el (comp-deferred-compilation): Remove
	customize.