Set tempest lock_path to default in $DATA_DIR

Change I464edf9e11710e1931ed4f7b0262328a57e5b3de set the tempest
lock_path to be $TMPDIR, however when run in the gate this is an
empty string which results in all tests that use locking failing.
This commit corrects that by setting the lock_path config variable
to use $TEMPEST_STATE_PATH which defaults to $DATA_DIR/tempest.

Change-Id: I02fbd50ca68d6daafb5b4c23579473eb703ae72a

Author: Matthew Treinish

lib/tempest

@@ -42,6 +42,7 @@ set +o xtrace
 TEMPEST_DIR=$DEST/tempest
 TEMPEST_CONF_DIR=$TEMPEST_DIR/etc
 TEMPEST_CONF=$TEMPEST_CONF_DIR/tempest.conf
+TEMPEST_STATE_PATH=${TEMPEST_STATE_PATH:=$DATA_DIR/tempest}
 
 NOVA_SOURCE_DIR=$DEST/nova
 
@@ -196,7 +197,8 @@ function configure_tempest() {
     fi
 
     # Oslo
-    iniset $TEMPEST_CONF DEFAULT lock_path $TMPDIR
+    iniset $TEMPEST_CONF DEFAULT lock_path $TEMPEST_STATE_PATH
+    mkdir -p $TEMPEST_STATE_PATH
 
     # Timeouts
     iniset $TEMPEST_CONF compute build_timeout $BUILD_TIMEOUT