makefile.unix: add sharpyuv objects to clean target
makefile.unix: add sharpyuv objects to clean target

Change-Id: Iad9ac2530bd892681c055e5ae1bf82eb8782d2a2

webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp