IVGCVSW-2056 + IVGCVSW-2064 : move ClContextControl to the ClBackend

Change-Id: Ice19d3f763298bc14585267df389e99df846320d
diff --git a/src/backends/reference/RefBackend.cpp b/src/backends/reference/RefBackend.cpp
index 34348fa..3aa4f03 100644
--- a/src/backends/reference/RefBackend.cpp
+++ b/src/backends/reference/RefBackend.cpp
@@ -9,8 +9,6 @@
 
 #include <backends/BackendRegistry.hpp>
 
-#include <boost/cast.hpp>
-
 namespace armnn
 {
 
@@ -21,7 +19,7 @@
 {
     BackendRegistryInstance(),
     RefBackend::GetIdStatic(),
-    []()
+    [](const EmptyInitializer&)
     {
         return IBackendInternalUniquePtr(new RefBackend);
     }