Remove duplicated test files

Even if they used to test different things in the past, they are
now identical to other files.

Closes #11496

Author: Sawyer47

src/test/compile-fail/issue-2123.rs

@@ -11,7 +11,10 @@
 
 use std::hash::hash;
 
-#[deriving(PartialEq, Clone, Hash)]
+// testing mulptiple separate deriving attributes
+#[deriving(PartialEq)]
+#[deriving(Clone)]
+#[deriving(Hash)]
 struct Foo {
     bar: uint,
     baz: int