d: Fix ICE in gimplify_expr with const ref noreturn parameters [PR123046]

The ICE was caused by references to const/immutable qualified `noreturn'
declarations that were being leaked to the code generation when they
should have been omitted or replaced with `assert(0)'.

	PR d/123046

gcc/d/ChangeLog:

	* d-codegen.cc (build_address): Return `null' when generating the
	address of a `noreturn' declaration.
	(d_build_call): Compare TYPE_MAIN_VARIANT of type with `noreturn'.
	* decl.cc (get_fndecl_arguments): Likewise.
	* types.cc (finish_aggregate_mode): Likewise.
	(TypeVisitor::visit (TypeFunction *)): Likewise.

gcc/testsuite/ChangeLog:

	* gdc.dg/pr123046.d: New test.

(cherry picked from commit b4ee1a549eac8d165740616376beeab73c5c6512)