AST: remove extra copy constructors

Visual Studio objects with the following:

```
  AST/AnyRequest.h(243): error: C2580: 'swift::AnyRequest::AnyRequest(const swift::AnyRequest &)': multiple versions of a defaulted special member functions are not allowed
  AST/AnyRequest(243): warning C4521: 'swift::AnyRequest': multiple copy constructors specified
```

Remove the non-const implementation, the default'ed definition should be
sufficient.  Additionally, remove the nonsense const move constructor.

Author: compnerd

include/swift/AST/AnyRequest.h

@@ -158,12 +158,6 @@ class AnyRequest {
     return *this;
   }
 
-  AnyRequest(AnyRequest &other)
-    : storageKind(other.storageKind), stored(other.stored) { }
-
-  AnyRequest(const AnyRequest &&other)
-    : storageKind(other.storageKind), stored(other.stored) { }
-
   // Create a local template typename `ValueType` in the template specialization
   // so that we can refer to it in the SFINAE condition as well as the body of
   // the template itself.  The SFINAE condition allows us to remove this