Backends: Win32: Optimized the Gamepad input processing part

[MidTerm-CN]

According to the official documentation of Xinput, I found that there is code that can be optimized and done.

The point of the optimization is that there is no need to add events when there is no Gamepad input, and the new code does not add events for unupdated data

Document: https://learn.microsoft.com/en-us/windows/win32/api/XInput/ns-xinput-xinput_state

[ocornut]

Hello,

Thanks for the PR. I am not sure this would be meaningful optimization given the added complexity. Did you profile the code to measure how much there was to gain? AddInputEvent() already does a backward search for the value.

However the dwPacketNumber compare seems useful and very easy to add.