fix gopath when building debs

Signed-off-by: Jessica Frazelle <acidburn@docker.com>

hack/make/build-deb

@@ -52,12 +52,14 @@ set -e
 			FROM $image
 			WORKDIR /usr/src/docker
 			COPY . /usr/src/docker
+			RUN mkdir -p /go/src/github.com/docker \
+				&& ln -snf /usr/src/docker /go/src/github.com/docker/docker
 		EOF
 		if [ "$DOCKER_EXPERIMENTAL" ]; then
 			echo 'ENV DOCKER_EXPERIMENTAL 1' >> "$DEST/$version/Dockerfile.build"
 		fi
 		cat >> "$DEST/$version/Dockerfile.build" <<-EOF
-			RUN go build -o aagen contrib/apparmor/*.go \
+			RUN GOPATH=/go go build -o aagen contrib/apparmor/*.go \
 				&& ./aagen contrib/apparmor/docker-engine
 			RUN ln -sfv hack/make/.build-deb debian
 			RUN { echo '$debSource (${debVersion}-0~${suite}) $suite; urgency=low'; echo; echo '  * Version: $VERSION'; echo; echo " -- $debMaintainer  $debDate"; } > debian/changelog && cat >&2 debian/changelog