Merge pull request #150 from Unity-Technologies/zxw/fix_missing_api_crash

temporary fix on editor crash (2019.4.26f1c1)

engine/src/shell/platform/unity/android/uiwidgets_system.h

 
   void PostTaskToGfxWorker(const fml::closure& task);
   void printf_console(const char* log, ...) {
-    va_list vl;
+    /*va_list vl;
-    va_end(vl);
+    va_end(vl);*/
   }
 
   void BindUnityInterfaces(IUnityInterfaces* unity_interfaces);

engine/src/shell/platform/unity/darwin/ios/uiwidgets_system.h

 
   void PostTaskToGfxWorker(const fml::closure& task);
   void printf_console(const char* log, ...) {
-    va_list vl;
+    /*va_list vl;
-    va_end(vl);
+    va_end(vl);*/
   }
 
   void BindUnityInterfaces(IUnityInterfaces* unity_interfaces);

engine/src/shell/platform/unity/darwin/macos/uiwidgets_system.h

 
   void PostTaskToGfxWorker(const fml::closure& task);
   void printf_console(const char* log, ...) {
-    va_list vl;
+    /*va_list vl;
-    va_end(vl);
+    va_end(vl);*/
   }
 
   void BindUnityInterfaces(IUnityInterfaces* unity_interfaces);

engine/src/shell/platform/unity/windows/uiwidgets_system.h

 
   void PostTaskToGfxWorker(const fml::closure& task);
   void printf_console(const char* log, ...) {
-    va_list vl;
+    /*va_list vl;
-    va_end(vl);
+    va_end(vl);*/
   }
 
   void BindUnityInterfaces(IUnityInterfaces* unity_interfaces);

engine/third_party/Unity/IUnityUIWidgets.h

   virtual void SetWakeUpCallback(VoidCallback callback) = 0;
   virtual void IssuePluginEventAndData(UnityRenderingEventAndData callback,
                                        int eventId, void* data) = 0;
-  virtual void printf_consolev(const char* log, va_list alist) = 0;
+  //TODO zxw: this API is not provided in 2019.4.26f1c1 due to a mistake :(
+  //we should consider adding it back later (remember to enable all callers too)
+  //virtual void printf_consolev(const char* log, va_list alist) = 0;
 };
 }  // namespace UnityUIWidgets