Removed redundant prototype after upstream added it too

Author: azonenberg

backends/imgui_impl_glfw.cpp

@@ -223,9 +223,6 @@ static void ImGui_ImplGlfw_ShutdownMultiViewportSupport();
 
 // Functions
 
-//Prototype to avoid -Werror=missing-declarations warning
-ImGuiKey ImGui_ImplGlfw_KeyToImGuiKey(int keycode, int scancode);
-
 // Not static to allow third-party code to use that if they want to (but undocumented)
 ImGuiKey ImGui_ImplGlfw_KeyToImGuiKey(int keycode, int scancode);
 ImGuiKey ImGui_ImplGlfw_KeyToImGuiKey(int keycode, int scancode)