[jenkins] Marvell armhf build improvements (sonic-net#205)

This commit addresses issues observed when building for Marvell
armhf. Specifically the following changes are being made.

1. Skip building the debug image for now so that the regular image can be made
   available in a more timely manner.
2. Do not remove the generated sonic-slave docker image so that it can be
   re-used by a subsequent build.
3. Add logic to cleanup the docker daemon avoiding potential interference with
   a subsequent build.
4. Remove multi-arch build artifacts to avoid an out of disk space issue on
   subsequent builds.

jenkins/marvell-armhf/buildimage-mrvl-armhf-all/Jenkinsfile

@@ -39,10 +39,19 @@ pipeline {
 git submodule foreach --recursive '[ -f .git ] && echo "gitdir: $(realpath --relative-to=. $(cut -d" " -f2 .git))" > .git'
 export DOCKER_DATA_ROOT_FOR_MULTIARCH=/data/march/docker
 make configure PLATFORM=marvell-armhf PLATFORM_ARCH=armhf
-make SONIC_BUILD_JOBS=4 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=2 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=1 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin
-mv target/sonic-marvell-armhf.bin target/sonic-marvell-armhf-dbg.bin
+#
+# Skip debug build for now until build time improvements can be made
+# make SONIC_BUILD_JOBS=4 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=2 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=1 INSTALL_DEBUG_TOOLS=y target/sonic-marvell-armhf.bin
+# mv target/sonic-marvell-armhf.bin target/sonic-marvell-armhf-dbg.bin
+#
+# Build as much as we can concurrently, backing off if failure
 make SONIC_BUILD_JOBS=4 target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=2 target/sonic-marvell-armhf.bin || make SONIC_BUILD_JOBS=1 target/sonic-marvell-armhf.bin
-sudo docker -H unix:///var/run/march/docker.sock system prune -f
+#
+# Cleanup for next build (dockerd and docker multi-arch artifacts)
+if sudo [ -f dockerfs/var/run/docker.pid ] ; then
+    pid=`sudo cat dockerfs/var/run/docker.pid` ; sudo kill $pid
+fi
+sudo rm -rf ${DOCKER_DATA_ROOT_FOR_MULTIARCH}
 '''
             }
         }