ensure BUCK built bits are used on stc

- Note: envDefaults internally checks bits timestamp to use latest bits.

Change-Id: Id5852b731432fca64397ea24dea1713f432a6329
diff --git a/tools/test/bin/stc b/tools/test/bin/stc
index 8a47e8d..7769057 100755
--- a/tools/test/bin/stc
+++ b/tools/test/bin/stc
@@ -3,6 +3,8 @@
 #   System Test Coordinator
 #-------------------------------------------------------------------------------
 
+. $ONOS_ROOT/tools/build/envDefaults
+
 VER=${STC_VERSION:-2.0}
 JAR=~/.m2/repository/org/onosproject/onos-stc/$VER/onos-stc-$VER.jar
 SCENARIOS=$ONOS_ROOT/tools/test/scenarios