/usr/bin/ld: Undefined symbols:
_main
_SDL_Delay
_SDL_DisplayFormat
_SDL_Flip
_SDL_FreeSurface
_SDL_GetError
_SDL_Init
_SDL_LoadBMP_RW
_SDL_Quit
_SDL_RWFromFile
_SDL_SetVideoMode
_SDL_UpperBlit
collect2: ld returned 1 exit status