linux-phytec-fsl

rcutorture: Don't rebuild identical kernel

Currently, if the user specifies multiple runs of a given test
configuration, the scripting does multiple kernel builds.  This wastes
both time and disk space, so this commit makes the scripting use the
first build for all runs of a given test configuration.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>