Add stronger checking

- Add assertions to enforce that objects are of the correct kind and
  have been allocated.

- Make destructors check if objects have been allocated before
  deleting.

- Operations that require a non-NullDevice return failure if given a
  NullDevice.

- Use static_cast rather than reinterpret_cast when cohersing from a
  base class to a derived class.

Change-Id: I02ee0ea9d7982fd7ca29d49c9b02cfae111b7127

rocclr/device/rocm/rocdevice.cpp

@@ -598,6 +598,7 @@ bool Device::create() {
   }
 
   // Create HSA settings
+  assert(!settings_);
   settings_ = new Settings();
   roc::Settings* hsaSettings = static_cast<roc::Settings*>(settings_);
   if ((hsaSettings == nullptr) ||