Update revision of commit-message-length-validator plugin

- Remove Buck based build
- Prefer using Splitter to String.split

Change-Id: Icf588a3f38713b379a0e3847752c5c5852273139
diff --git a/plugins/commit-message-length-validator b/plugins/commit-message-length-validator
index 07b5f22..315a115 160000
--- a/plugins/commit-message-length-validator
+++ b/plugins/commit-message-length-validator
@@ -1 +1 @@
-Subproject commit 07b5f220ec6e7e08d5483c2e6248f6145d30712e
+Subproject commit 315a11558913fa8f9c6d3b1723e45583b25afa1c