[cexpr] Correct bool's backing value type

Using int instead of bool probably won't work well if QF ever finds
itself on a big-endian system again.

libs/util/cexpr-type.c

@@ -108,7 +108,7 @@ exprtype_t cexpr_bool = {
 	.get_string = bool_get_string,
 };
 
-static int bool_values[] = {
+static bool bool_values[] = {
 	false,
 	true,
 };