Make sure that the norms are positive in Beamformer

This has a bit exact output, but is just to be sure that there are no nummerical errors when the covariance matrices are nearly singular.

R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/39019004

Cr-Commit-Position: refs/heads/master@{#8316}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8316 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed