sdl2_image依赖安装失败

Reproduce the failure with xmake f -a aarch64 and inspect the sdl2_image 2.0.5 installation output around IMG_webp.c. Check how the aarch64-smart-musleabi build obtains webp/decode.h and how this dependency is handled for the target. Done means the dependency installs successfully without the missing-header error.

系统：debian 12
xmake版本：v2.8.3+20231018,
执行命令xmake f -a aarch64时，显示

  => install aarch64-smart-musleabi 188177 .. ok
  => download https://github.com/libsdl-org/SDL_image/archive/refs/tags/release-2.0.5.tar.gz .. ok
  => install sdl2_image 2.0.5 .. failed

具体报错情况如下：

...
mv -f .deps/IMG_WIC.Tpo .deps/IMG_WIC.Plo
mv -f .deps/showimage.Tpo .deps/showimage.Po
IMG_webp.c:42:10: fatal error: webp/decode.h: No such file or directory
   42 | #include <webp/decode.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:619: IMG_webp.lo] Error 1
make: *** Waiting for unfinished jobs....
mv -f .deps/IMG_tif.Tpo .deps/IMG_tif.Plo
mv -f .deps/IMG_pcx.Tpo .deps/IMG_pcx.Plo
mv -f .deps/IMG_xv.Tpo .deps/IMG_xv.Plo
mv -f .deps/IMG_pnm.Tpo .deps/IMG_pnm.Plo
mv -f .deps/IMG.Tpo .deps/IMG.Plo
mv -f .deps/IMG_tga.Tpo .deps/IMG_tga.Plo
mv -f .deps/IMG_jpg.Tpo .deps/IMG_jpg.Plo
mv -f .deps/IMG_xpm.Tpo .deps/IMG_xpm.Plo
mv -f .deps/IMG_lbm.Tpo .deps/IMG_lbm.Plo
mv -f .deps/IMG_gif.Tpo .deps/IMG_gif.Plo
mv -f .deps/IMG_bmp.Tpo .deps/IMG_bmp.Plo
mv -f .deps/IMG_xcf.Tpo .deps/IMG_xcf.Plo
mv -f .deps/IMG_png.Tpo .deps/IMG_png.Plo
mv -f .deps/IMG_svg.Tpo .deps/IMG_svg.Plo