Update Buck

Buck does not accept duplicate resources, which happens with
gwt_module() loading in srcs, resources and gwt_xml. Convert
to a set and back to a list to remove duplicates transparently.

Contributed-by: Shawn Pearce <sop@google.com>
Change-Id: Ic27ab2f34c60c8cb54373d93fcd0c7cac7477a3b

buckversion

diff --git a/buckversion b/buckversion
index a0c6bc2..62da292 100644
--- a/buckversion
+++ b/buckversion
@@ -1 +1 @@
-0fe4569e871fd6588f7cbfb4b1d4a14baa791a9f
+620fdf494f66c2876cfc7cae6f6feb9d36e45df4

gwt_module.bucklet

diff --git a/gwt_module.bucklet b/gwt_module.bucklet
index d62c44a..461cd2d 100644
--- a/gwt_module.bucklet
+++ b/gwt_module.bucklet
@@ -26,4 +26,9 @@
     kw['resources'] += [gwt_xml]
   if 'srcs' in kw:
     kw['resources'] += kw['srcs']
+
+  # Buck does not accept duplicate resources. Callers may have
+  # included gwt_xml or srcs as part of resources, so de-dupe.
+  kw['resources'] = list(set(kw['resources']))
+
   java_library(**kw)