Test that built-ins cannot be bound to structs

Author: wechman

test/libsolidity/syntaxTests/using/free_functions_implicit_conversion_err.sol

@@ -1,8 +1,14 @@
+struct S {
+    uint8 x;
+}
+
 function id(uint16 x) pure returns(uint16) {
     return x;
 }
 contract C {
     using {id} for uint256;
+    using {id} for S;
 }
 // ----
-// TypeError 3100: (85-87): The function "id" cannot be bound to the type "uint256" because the type cannot be implicitly converted to the first argument of the function ("uint16").
+// TypeError 3100: (112-114): The function "id" cannot be bound to the type "uint256" because the type cannot be implicitly converted to the first argument of the function ("uint16").
+// TypeError 3100: (140-142): The function "id" cannot be bound to the type "struct S storage pointer" because the type cannot be implicitly converted to the first argument of the function ("uint16").