Nativecomp don't materialize non-materializable objects (bug#78606)

Nativecomp don't materialize non-materializable objects (bug#78606)

The native compiler should not try to generate in rendered code
immediate floats produced by the constrain on the '=' operator.

* test/src/comp-tests.el (comp-test-78606-1): Add test.
* test/src/comp-resources/comp-test-funcs.el (comp-test-78606-1-f): New
function.
* src/comp.c (emit_mvar_rval): Check if an immediate is materializable.
* lisp/emacs-lisp/comp.el (comp-ctxt): Add 'non-materializable-objs-h'
slot.
(comp--fwprop-insn): Update call.
* lisp/emacs-lisp/comp-cstr.el (comp-cstr-=): Add parameter.

(cherry picked from commit 48a5917681dd53b8b75764f4e1455a6c24f95498)