contrib/jenkins.sh: run "make maintainer-clean"

Related: OS#3047
Change-Id: I6f9274efeb2fdda54feaa54eb299f7aafaaec1eb
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index 617aeac..5754f2c 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -55,5 +55,6 @@
   || cat-testlogs.sh
 $MAKE distcheck \
   || cat-testlogs.sh
+$MAKE maintainer-clean
 
 osmo-clean-workspace.sh