librustc: Allow trait bounds on structures and enumerations, and check

them during kind checking.

This implements RFC #11.

Closes #15759.

src/test/compile-fail/deriving-span-Zero-tuple-struct.rs

@@ -16,9 +16,11 @@ extern crate rand;
 
 struct Error;
 
-#[deriving(Zero)]
+#[deriving(Zero)]   //~ ERROR failed to find an implementation
 struct Struct(
     Error //~ ERROR
+    //~^ ERROR failed to find an implementation
+    //~^^ ERROR type `Error` does not implement any method in scope
 );
 
 fn main() {}