build temu error about SDL

1. 安装sdl2

sudo apt-get install libsdl2-dev

　　

2. 将configure文件中与SDL有关的地方改成SDL2

if test -z "$sdl" ; then
    sdl_config="sdl2-config"
    sdl=no

　　

cat > $TMPC << EOF
#include <SDL2/SDL.h>
#undef main /* We don't want SDL to override our main() */