Use patched aufs-utils so can compile kernel with alpine

This is going to be submitted upstream.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/base/alpine-build-c/Dockerfile

@@ -1,2 +1,22 @@
 FROM alpine:3.4
-RUN apk update && apk upgrade && apk add build-base util-linux-dev linux-headers
+RUN \
+  apk update && apk upgrade && \
+  apk add \
+  alpine-sdk \
+  automake \
+  bash \
+  bc \
+  curl \
+  gmp-dev \
+  installkernel \
+  kmod \
+  linux-headers \
+  perl \
+  sed \
+  squashfs-tools \
+  syslinux \
+  unzip \
+  util-linux-dev \
+  vim \
+  xz \
+  && true