gccrs: Add variadic argument type checking

gcc/rust/ChangeLog:

	* typecheck/rust-tyty-call.cc
	(TypeCheckCallExpr::visit): Add variadic argument type checking.
	(TypeCheckCallExpr::visit): Fix comment spelling ("varadic").

gcc/testsuite/ChangeLog:

	* rust/execute/torture/overflow1.rs: Fix test.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>