Commit 3114874713 delegated PCX loading to SDL_image, and as an incidental change, switched to using an unbuffered PHYSFS file. On Linux, this has no perceptible difference in performance. On Windows, the unbuffered accesses cause enough of a performance problem for users to notice and report an issue. Add a new helper to create an SDL_RWops around a buffered file, and use that for PCX loading. Fixes: 3114874713 ("Delegate PCX loading to SDL_image") Reported-by: Q3BFG10K <https://github.com/dxx-rebirth/dxx-rebirth/issues/549> Reported-by: aybe <https://github.com/dxx-rebirth/dxx-rebirth/issues/555> Analyzed-by: arbruijn <https://github.com/dxx-rebirth/dxx-rebirth/issues/555#issuecomment-735442076>
3114874713