Previously, calling SDL_SendWindowEvent for a SIZED_CHANGED event would
filter the queue to remove RESIZED and SIZED_CHANGED events, so you don't
overflow the queue with obsolete data, but any RESIZED events would be
lost in this process.
Now we note if there was a RESIZED pending and replace it with a new
event using the same dimensions as the new SIZED_CHANGED event. This fixes
cases where an app is only listening for RESIZED events and thus might
lose important information in some cases.
Fixes#5925.
cf63af8ae2