Fix nativecomp cond-rw pass

Fix nativecomp cond-rw pass

	* lisp/emacs-lisp/comp.el (comp-mvar-symbol-p): Improve it.
	(comp-cond-rw-func): Fix logic for multiple predecessor on target
	block.
	* test/src/comp-tests.el (comp-test-cond-rw-1): New test.
	* test/src/comp-test-funcs.el (comp-test-cond-rw-1-1-f)
	(comp-test-cond-rw-1-2-f): New functions.