contrib/jenkins: Enable parallel make in make distcheck

Related: OS#4421
Change-Id: I54b084de6080ab8c438c2c85663abe01c54b07fe
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index 727cffe..b902cc6 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -38,8 +38,8 @@
 autoreconf --install --force
 ./configure --enable-sanitize --enable-werror --enable-e1d
 $MAKE $PARALLEL_MAKE
-$MAKE distcheck \
+$MAKE $PARALLEL_MAKE distcheck \
   || cat-testlogs.sh
-$MAKE maintainer-clean
+$MAKE $PARALLEL_MAKE maintainer-clean
 
 osmo-clean-workspace.sh