Allow TextVersion to be with 5 of actual version.  This allows a few changes without failing the unittest before version.h must be updated.  Note that changes of documentation count.
BUG=none
TEST=TestVersion passes, even though this CL purposely does not update the version.
Review URL: https://webrtc-codereview.appspot.com/781007

git-svn-id: http://libyuv.googlecode.com/svn/trunk@344 16f28f9a-4ce2-e073-06de-1de4eb20be90