add #ifdefs for OSX-specific code

src/gui/update_checker.cpp

@@ -92,7 +92,9 @@ bool update_available()  {
 class CheckUpdateThread : public wxThread {
 public:
   void* Entry() override {
-//    Work();
+    #ifndef __APPLE__
+        Work();
+    #endif
     return 0;
   }