Update Buck

java_library() now accepts provided_deps argument which replaces
our custom use of java_library2().

This change replaces compile_deps with provided_deps parameter in
gerrit_{plugin,extension} rules. Plugins that are using it must be
updated.

Change-Id: I16d53793da567c958267f91ca203e9cae6c4d02f
diff --git a/tools/build.defs b/tools/build.defs
index af39c2a..5c01e8f 100644
--- a/tools/build.defs
+++ b/tools/build.defs
@@ -33,7 +33,7 @@
   deps = []
   for n in os.listdir('plugins'):
     if os.path.exists(os.path.join('plugins', n, 'BUCK')):
-      deps.append('//plugins/%s:%s__plugin__compile' % (n, n))
+      deps.append('//plugins/%s:%s__plugin' % (n, n))
   return deps
 
 def war(