test/jenkins: add job to test pre-dump

Make pre-dump twice and then dump and restore.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/jenkins/criu-pre-dump.sh

+# Check pre-dump
+
+source `dirname $0`/criu-lib.sh &&
+prep &&
+mkdir -p test/dump &&
+mount -t tmpfs dump test/dump &&
+make -C test -j 4 'ZDTM_ARGS=-P -i 3 -C' &&
+true || fail