[NaCl SDK] Fix nacl SDK build

This was broken by https://chromium-review.googlesource.com/728950

Change-Id: I913650b267bb42ee9d4bf0d64b03b22eadb9f04a
Reviewed-on: https://chromium-review.googlesource.com/900295Reviewed-by: Derek Schuff <dschuff@chromium.org>
Commit-Queue: Sam Clegg <sbc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534196}

native_client_sdk/src/build_tools/build_version.py

@@ -115,7 +115,7 @@ def FetchCommitPosition(directory=None):
     for line in reversed(lines):
       if line.startswith('Cr-Commit-Position:'):
         pos = line.rsplit()[-1].strip()
-        return lastchange.VersionInfo('%s-%s' % (hsh, pos))
+        return lastchange.VersionInfo(hsh, '%s-%s' % (hsh, pos))
 
   raise Exception('Unable to fetch a Git Commit Position.')