message: remove global variable in header file
diff: extern "C" {
  #endif
  -/*
  - * This is the super set of all extension functions we support in onnxifi.
  - * All backend should support a subset of function of this list.
  - */
  -static const int ALL_EXT_FUNCTION_NUMBER = 2;
  -static const char* ALL_EXT_FUNCTION_LIST[] = {"onnxGetExtensionFunctionAddress",
  - "onnxSetIOAndRunGraph"};
  -
  /**
  * Generic ONNXIFI extension function pointer.
  *
  