Link QNN backend to pybinding lib when built

ghstack-source-id: d25cb2e
ghstack-comment-id: 3194008742
Pull-Request: #13467

Author: GregoryComer

CMakeLists.txt

@@ -831,6 +831,10 @@ if(EXECUTORCH_BUILD_PYBIND)
     list(APPEND _dep_libs openvino_backend)
   endif()
 
+if(EXECUTORCH_BUILD_QNN)
+  list(APPEND _dep_libs qnn_executorch_backend)
+endif()
+
   if(EXECUTORCH_BUILD_XNNPACK)
     # need to explicitly specify XNNPACK and xnnpack-microkernels-prod here
     # otherwise uses XNNPACK and microkernel-prod symbols from libtorch_cpu