Fixed duplicate symbols in some compile-time configurations.

imgui_demo.cpp

@@ -10776,7 +10776,6 @@ void ImGui::ShowDemoWindow(bool*) {}
 void ImGui::ShowUserGuide() {}
 void ImGui::ShowStyleEditor(ImGuiStyle*) {}
 bool ImGui::ShowStyleSelector(const char*) { return false; }
-void ImGui::ShowFontSelector(const char*) {}
 
 #endif // #ifndef IMGUI_DISABLE_DEMO_WINDOWS