update ChangeLog
update ChangeLog

Change-Id: I0d8730f3f5fb0b54404666bc0088fe29a3e55fc4

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