* Nativecomp testsuite rework for derived return type specifiers

* Nativecomp testsuite rework for derived return type specifiers

As we have derived return type specifiers as some test for them.  Also
rewrite some propagation related test using return type specifiers too
as it's way more convenient.

	* test/src/comp-tests.el (fw-prop-1): Nit rename.
	(comp-tests-check-ret-type-spec): New function.
	(comp-tests-type-spec-tests): New variable.
	(comp-tests-cond-rw-0-var) Remove variable.
	(cond-rw-0, cond-rw-1, cond-rw-2, cond-rw-3, cond-rw-4, cond-rw-5)
	Remove tests as now covered by `comp-tests-check-ret-type-spec'.