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

Related: OS#3047
Change-Id: Ib261f25e2c7b48283a6142259991aadfcf40cdec
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index 6a76044..a465d5a 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -37,5 +37,6 @@
 $MAKE $PARALLEL_MAKE
 $MAKE distcheck \
   || cat-testlogs.sh
+$MAKE maintainer-clean
 
 osmo-clean-workspace.sh