This fixes the following warning from a recent version of Clang:

  base/linux.cc:229:36: error: comparison of constant -1 with expression of type
'talk_base::StreamResult' is always false
[-Werror,-Wtautological-constant-out-of-range-compare]

BUG=crbug.com/163104
TBR=hans@chromium.org
Review URL: https://webrtc-codereview.appspot.com/935026

git-svn-id: http://libjingle.googlecode.com/svn/trunk@245 dd674b97-3498-5ee5-1854-bdd07cd0ff33