Update DOCKER_CROSSPLATFORMS to be more readable

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

Dockerfile

@@ -68,7 +68,10 @@ ENV	GOPATH	/go:/go/src/github.com/dotcloud/docker/vendor
 RUN	cd /usr/local/go/src && ./make.bash --no-clean 2>&1
 
 # Compile Go for cross compilation
-ENV	DOCKER_CROSSPLATFORMS	linux/386 linux/arm darwin/amd64 darwin/386 freebsd/amd64 freebsd/386 freebsd/arm
+ENV	DOCKER_CROSSPLATFORMS	\
+	linux/386 linux/arm \
+	darwin/amd64 darwin/386 \
+	freebsd/amd64 freebsd/386 freebsd/arm
 # (set an explicit GOARM of 5 for maximum compatibility)
 ENV	GOARM	5
 RUN	cd /usr/local/go/src && bash -xc 'for platform in $DOCKER_CROSSPLATFORMS; do GOOS=${platform%/*} GOARCH=${platform##*/} ./make.bash --no-clean 2>&1; done'