Update to new tfkit (g122272a)

utils/tfkit/runtests

 export TF_ARTIFACTS="${TF_ARTIFACTS:-tfkit-artifacts}"
 export TF_COLLECT="${TF_COLLECT:-auto}"
 
-. $TF_DIR/include/harness.sh || die "this must be run from project root"
+. $TF_DIR/include/harness.sh \
+ || die "cannot import harness; is TF_DIR set properly?: $TF_DIR"
 
 
 usage() {