imgui: remove other gl loaders

src/imgui/imgui_impl_opengl3.h

@@ -57,26 +57,7 @@ IMGUI_IMPL_API void ImGui_ImplOpenGL3_DestroyDeviceObjects();
 #define IMGUI_IMPL_OPENGL_ES3  // iOS, Android  -> GL ES 3, "#version 300 es"
 #elif defined(__EMSCRIPTEN__)
 #define IMGUI_IMPL_OPENGL_ES2  // Emscripten    -> GL ES 2, "#version 100"
-
-// Otherwise try to detect supported Desktop OpenGL loaders..
-#elif defined(__has_include)
-#if __has_include(<GL/glew.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GLEW
-#elif __has_include(<glad/glad.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GLAD
-#elif __has_include(<glad/gl.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GLAD2
-#elif __has_include(<GL/gl3w.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GL3W
-#elif __has_include(<glbinding/glbinding.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GLBINDING3
-#elif __has_include(<glbinding/Binding.h>)
-#define IMGUI_IMPL_OPENGL_LOADER_GLBINDING2
-#else
-#error "Cannot detect OpenGL loader!"
-#endif
-#else
-#define IMGUI_IMPL_OPENGL_LOADER_GL3W  // Default to GL3W embedded in our repository
 #endif
 
+#define IMGUI_IMPL_OPENGL_LOADER_GLAD
 #endif