Revert "Fix locking for printing error messages."

This reverts commit 187b3dfab5cca45e2af192bf7f5db09bcc156314.

A unit test fails when it shouldn't.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4138

Review URL: https://codereview.chromium.org/1071423003
6 files changed