IVGCVSW-2454 Merge together the pluggable backends work (was in a
separate branch) and master

 * Brings in all the changes done for the pluggable backends
 * Added sub-graph support and tests
 * Added precompiled layer support and tests
 * Moved BackendSettings to a separate file
 * Removed the backend-specific code
 * Ported DebugLayer and associated functionality
 * Included fixes to make those changes work with master

Change-Id: Id7028fa7917527b844628d5aff5732e3d94c0488
diff --git a/src/backends/cl/ClBackend.cpp b/src/backends/cl/ClBackend.cpp
index 2b82c18..2f9dfa9 100644
--- a/src/backends/cl/ClBackend.cpp
+++ b/src/backends/cl/ClBackend.cpp
@@ -63,6 +63,12 @@
     return IBackendContextPtr{new ClBackendContext{options}};
 }
 
+IBackendInternal::ISubGraphConverterPtr ClBackend::CreateSubGraphConverter(
+    const std::shared_ptr<SubGraph>& subGraph) const
+{
+    return ISubGraphConverterPtr{};
+}
+
 IBackendInternal::Optimizations ClBackend::GetOptimizations() const
 {
     return Optimizations{};