Add additional error printing to kqueue failures on Mac.
Add additional error printing to kqueue failures on Mac.

This is an attempt to get more information on dartbug.com/1876

R=ricow@google.com
BUG=1876

Review URL: https://chromiumcodereview.appspot.com//9705096

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@5686 260f80e4-7a28-3924-810f-c04153c831b5

dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk