Examples: SDL2+OpenGL3: Fix context creation options (#468, #463)

examples/sdl_opengl3_example/main.cpp

@@ -17,10 +17,12 @@ int main(int, char**)
 	}
 
     // Setup window
-	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
 	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
 	SDL_DisplayMode current;
 	SDL_GetCurrentDisplayMode(0, &current);