update ChangeLog
update ChangeLog

Change-Id: Ia3faaafd42eb96e257415e1cf9c7ceb69f851147

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