Bazel: Bump baseline to 0.17.1

New Bazel version is using JDK 9 javac. That will allow us to target
JDK 9 in Gerrit build.

Change-Id: I86666a9fda21c55852c64373bca2131ef0572c72
diff --git a/WORKSPACE b/WORKSPACE
index 923c78e..e9fc1dd 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -30,7 +30,7 @@
 
 load("@bazel_skylib//:lib.bzl", "versions")
 
-versions.check(minimum_bazel_version = "0.14.0")
+versions.check(minimum_bazel_version = "0.17.1")
 
 load("@io_bazel_rules_closure//closure:defs.bzl", "closure_repositories")