futility: stop using the symlink names in utility scripts

We still create the symlinks (FOO -> futility), but this
change invokes those built-in functions with "futility FOO ..."
instead of using the FOO symlink.

Note that the scripts/ directory is unchanged. That's a
separate CL, since we don't have tests for that.

BUG=chromium:231547
BRANCH=ToT
TEST=make runtests

In addition to running "make runtests", I temporarily
modified the Makefile to avoid creating the symlinks at all.
The tests still passed.

Change-Id: I96863259b9df02a3611f759a7509bf4090ae03e8
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/216717
Reviewed-by: Randall Spangler <rspangler@chromium.org>
diff --git a/tests/common.sh b/tests/common.sh
index 5ae5629..5a96343 100644
--- a/tests/common.sh
+++ b/tests/common.sh
@@ -10,6 +10,7 @@
 ROOT_DIR="$(dirname ${SCRIPT_DIR})"
 BUILD_DIR="${BUILD}"
 BIN_DIR="${BUILD_DIR}/install_for_test"
+FUTILITY=${BIN_DIR}/futility
 TEST_DIR="${BUILD_DIR}/tests"
 TESTKEY_DIR=${SCRIPT_DIR}/testkeys
 TESTCASE_DIR=${SCRIPT_DIR}/testcases