dec/webp: use GetLE(24|32) from utils
dec/webp: use GetLE(24|32) from utils

picks up the undefined behavior fix from the previous commit

BUG=278

Change-Id: Ie17bf7db827b1dc564194aadcf6c5e47f61681f7

PKRoma/libwebp,redengineer/libwebp,ttyangf/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,redengineer/libwebp,webmproject/libwebp,redengineer/libwebp,webmproject/libwebp,redengineer/libwebp,ttyangf/libwebp,redengineer/libwebp,ttyangf/libwebp,ttyangf/libwebp,PKRoma/libwebp,PKRoma/libwebp,ttyangf/libwebp,PKRoma/libwebp