Initial support for union of negated constraints

Initial support for union of negated constraints

	* lisp/emacs-lisp/comp-cstr.el (comp-range-negation): New
	function.
	(comp-cstr-union-homogeneous-no-range): Rename from
	`comp-cstr-union-no-range'.
	(comp-cstr-union-homogeneous): Rename from `comp-cstr-union'.
	(comp-cstr-union-1): New function.
	(comp-cstr-union-no-range, comp-cstr-union): Rewrite in function
	of `comp-cstr-union-1'.
	* test/lisp/emacs-lisp/comp-cstr-tests.el
	(comp-cstr-typespec-tests-alist): Add a bunch of tests.