build: Fix allcross build due to lz4

liblz4-tool has vanished from debian, lz4 should install what we need.

Author: mpe

build/allcross/Dockerfile

@@ -38,7 +38,7 @@ RUN apt-get -q -y update && \
       libc-dev \
       libelf-dev \
       libfuse-dev \
-      liblz4-tool \
+      lz4 \
       libssl-dev \
       lzop \
       make \