gccrs: backend: Add overflow checks to every arithmetic operation

gccrs: backend: Add overflow checks to every arithmetic operation

gcc/rust/ChangeLog:

	* backend/rust-compile-expr.cc (CompileExpr::visit): Insert overflow
	checks logic.
	(CompileExpr::array_copied_expr): Insert overflow checks logic.
	* backend/rust-compile-item.cc (CompileItem::visit): Insert overflow
	checks logic.
	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): Insert
	overflow checks logic.
	* rust-gcc.cc (Gcc_backend::arithmetic_or_logical_expression): Differentiate
	existing function from `arithmetic_or_logical_expression_checked`.
	This function does insert perform overflow checks.
	(Gcc_backend::arithmetic_or_logical_expression_checked): New
	function.
	(is_overflowing_expr): New function. Check if an expression is an
	overflowing one (ADD, SUB, MUL).
	(fetch_overflow_builtins): New function.
	* rust-backend.h: Declare `arithmetic_or_logical_expression_checked` in
	abstract `Backend` class.

gcc/testsuite/ChangeLog:

	* rust/debug/win64-abi.rs: Fix assertion to take into account
	overflow builtins
	* rust/compile/torture/macro-issue1426.rs: Moved to...
	* rust/execute/torture/macro-issue1426.rs: ...here.
	* rust/execute/torture/overflow1.rs: New test.