undo remove of statement due to compiler warning for unused variable

Instead, remove the unused variable assignment only

oxygine/src/oxygine/core/oxygine.cpp

@@ -402,8 +402,7 @@ namespace oxygine
             file::init(desc.companyName, desc.appName);
 
 #ifdef OXYGINE_SDL
- // unused variable (hotfix/compiler-warnings)
- //           int missing = initGLExtensions(SDL_GL_GetProcAddress);
+            initGLExtensions(SDL_GL_GetProcAddress);
 #endif
 
             Point size = getDisplaySize();