Increase max trace message size to 1024 characters.

A recent CL by pbos:
https://code.google.com/p/webrtc/source/detail?r=7518

added long log messages and triggered errors on the DrMemory bot due to
WEBRTC_TRACE. The trace mechanism _should_ truncate the log strings
but something appears to be going awry.

This sweeps the problem under the rug, but given that WEBRTC_TRACE
should die fairly soon, seems to be a reasonable tradeoff.

TEST=passing try on DrMemory.
R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/27849004

Patch from Andrew MacDonald <andrew@webrtc.org>.

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7526 4adac7df-926f-26a2-2b94-8c16560cd09d