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

Related: OS#3047
Change-Id: I78fc465169b9ed95a2f9aaef93f28e1ce47b551a
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index 8680cde..3b4e639 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -10,5 +10,6 @@
 $MAKE
 $MAKE $PARALLEL_MAKE
 $MAKE distcheck || cat-testlogs.sh
+$MAKE maintainer-clean
 
 osmo-clean-workspace.sh