Build virtualhost module on stable-3.15

Change-Id: Ic802f01bac7d3aa9da5d35d8b89fd7f8e8367d9c

jenkins/gerrit-bazel-module-virtualhost.yaml

diff --git a/jenkins/gerrit-bazel-module-virtualhost.yaml b/jenkins/gerrit-bazel-module-virtualhost.yaml
index 485e257..02eb34e 100644
--- a/jenkins/gerrit-bazel-module-virtualhost.yaml
+++ b/jenkins/gerrit-bazel-module-virtualhost.yaml
@@ -15,4 +15,5 @@
           branch:
             - master
           gerrit-branch:
+            - stable-3.15
             - stable-3.14