Add -logFile option to Bench
Add -logFile option to Bench

Logs to a file as well as stdout.  Useful for Android,
where logging takes a different format.
Review URL: https://codereview.appspot.com/6450095

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@4963 2bbb7eff-a529-9590-31e7-b0007b416f81

Cue/skia,mrobinson/skia,mrobinson/skia,mrobinson/skia,metajack/skia,Cue/skia,metajack/skia,Cue/skia,Cue/skia,metajack/skia,mrobinson/skia,metajack/skia,mrobinson/skia