Consume JGit artifacts from Maven Central

The recent JGit releases were published to the Eclipse repository
due to a security embargo. The embargo has since been lifted, and
the releases are available on Maven Central, so switch back to
consuming the artifacts from there.

Change-Id: I054cc91f410451fe2f3da5b3c8274d8b5890a3bf
diff --git a/lib/jgit/BUCK b/lib/jgit/BUCK
index 8c9e1c6..9a94085 100644
--- a/lib/jgit/BUCK
+++ b/lib/jgit/BUCK
@@ -1,6 +1,6 @@
 include_defs('//lib/maven.defs')
 
-REPO = ECLIPSE # Leave here even if set to MAVEN_CENTRAL.
+REPO = MAVEN_CENTRAL # Leave here even if set to MAVEN_CENTRAL.
 VERS = '4.5.5.201812240535-r'
 
 maven_jar(