Make starpu_smpirun return the value returned by smpirun

tools/starpu_smpirun.in

@@ -91,5 +91,7 @@ EOF
 STACKSIZE=$(ulimit -s)
 [ "$STACKSIZE" != unlimited ] || STACKSIZE=8192
 $SMPIRUN -platform $PLATFORM -hostfile $MPI_HOSTFILE "$@" --cfg=smpi/privatize_global_variables:yes --cfg=contexts/stack_size:$STACKSIZE
+RET=$?
 
 rm -f $PLATFORM
+exit $RET