Clean up build flavor usage and fix JNI native signature

app/src/common/shared/org/mozilla/vrbrowser/ui/widgets/settings/DisplayOptionsView.java

@@ -74,8 +74,7 @@ private void initialize(Context aContext) {
 
         mFoveatedAppRadio = findViewById(R.id.foveated_app_radio);
         mFoveatedWebVRRadio = findViewById(R.id.foveated_webvr_radio);
-        if (BuildConfig.FLAVOR_platform == "oculusvr" ||
-            BuildConfig.FLAVOR_platform == "wavevr") {
+        if (DeviceType.isOculusBuild() || DeviceType.isWaveBuild()) {
             mFoveatedAppRadio.setVisibility(View.VISIBLE);
             // Uncomment this when Foveated Rendering for WebVR makes more sense
             // mFoveatedWebVRRadio.setVisibility(View.VISIBLE);
@@ -316,7 +315,7 @@ private void setFoveatedLevel(RadioGroupSetting aSetting, int checkedId, boolean
         if (doApply) {
             mWidgetManager.updateFoveatedLevel();
             // "WaveVR WVR_RenderFoveation(false) doesn't work properly, we need to restart."
-            if (level == 0 && BuildConfig.FLAVOR_platform == "wavevr") {
+            if (level == 0 && DeviceType.isWaveBuild()) {
                 showRestartDialog();
             }
         }

app/src/main/cpp/BrowserWorld.cpp

@@ -1436,7 +1436,7 @@ JNI_METHOD(void, runCallbackNative)
 }
 
 JNI_METHOD(void, setCPULevelNative)
-(JNIEnv*, jobject, int aCPULevel) {
+(JNIEnv*, jobject, jint aCPULevel) {
   crow::BrowserWorld::Instance().SetCPULevel(static_cast<crow::device::CPULevel>(aCPULevel));
 }