able to comple with tex inspect

lib/backends/tex_inspect_opengl.h

@@ -0,0 +1,9 @@
+// ImGuiTexInspect, a texture inspector widget for dear imgui
+#pragma once
+
+#include <stddef.h>
+namespace ImGuiTexInspect
+{
+bool ImplOpenGL3_Init(const char *glsl_version = NULL);
+void ImplOpenGl3_Shutdown();
+} // namespace ImGuiTexInspect