jenkins: use tmpfs for images in criu-iter

It resuces I/O load.
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/jenkins/criu-iter.sh

@@ -2,5 +2,7 @@
 
 source `dirname $0`/criu-lib.sh &&
 prep &&
+mkdir -p test/dump &&
+mount -t tmpfs dump test/dump &&
 make -C test ZDTM_ARGS="-C -i 3 -x maps04" zdtm &&
 true || fail