[Ne0nWinds]

This PR fixes two different, yet related, issues that occurred when resizing the window with the software rasterizer enabled.

1. Underlying bitmap not resized

When the software rasterizer is enabled, the underlying window bitmap was not resized. If the window was resized to be smaller, the image would look garbled. If the window became larger, the application would crash from reading past the end of the bitmap.

Fix: Whenever the window width/height changes, resize the GDI bitmap the underlying GDI bitmap

2. WM_SIZE event ordering

This PR also fixes a hack that was put in place due to the ordering of Windows events. Upon window creation, Windows sends a WM_SIZE event (and potentially other related events like WM_GETDPISCALEDSIZE and WM_DPICHANGED). This is problematic because WndProc can call HandleWindowResize, which in turn, calls SetupViewport and swResize.

The software rasterizer is not initialized when InitPlatform is called, so calling SetupViewport or swResize will crash the program. In fact, there's already a hack in the WM_SIZE event to prevent this: if (CORE.Time.frameCounter > 2)

Fix: In this PR, I simply defer calling SetupViewport and swResize until PollInputEvents. The software rasterizer is guaranteed to be initialized by the time PollInputEvents is called, so we don't need to put any special cases into the event handlers

[raysan5]

@Ne0nWinds Nice improvement! Thanks!