Make is_type_lock_free follow what each target lowers without library calls, and reject atomics on types which are not lock-free

src/check_expr.cpp

@@ -6600,20 +6600,6 @@ gb_internal bool is_type_normal_pointer(Type *ptr, Type **elem) {
 	return false;
 }
 
-gb_internal bool is_type_valid_atomic_type(Type *elem) {
-	elem = core_type(elem);
-	if (is_type_internally_pointer_like(elem)) {
-		return true;
-	}
-	if (elem->kind == Type_BitSet) {
-		elem = bit_set_to_int(elem);
-	}
-	if (elem->kind != Type_Basic) {
-		return false;
-	}
-	return (elem->Basic.flags & (BasicFlag_Boolean|BasicFlag_OrderedNumeric)) != 0;
-}
-
 gb_internal bool check_identifier_exists(Scope *s, Ast *node, bool nested = false, Scope **out_scope = nullptr) {
 	switch (node->kind) {
 	case_ast_node(i, Ident, node);