enquote $@ so that enquoted args to test_that will work correctly

BUG=None
TEST=test_that works properly with --args="--potato=1 --carrot=2"

Change-Id: I1f8c68ed512c095f4405937643c8a2284c324364
Reviewed-on: https://gerrit.chromium.org/gerrit/64015
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
diff --git a/test_that b/test_that
index 0077613..6cfc369 100755
--- a/test_that
+++ b/test_that
@@ -14,7 +14,7 @@
 
 trap : SIGTERM SIGINT
 
-sudo $SCR $@ &
+sudo $SCR "$@" &
 child_pid=$!
 wait $child_pid