Trying to build glog with TSAN ends up causing a bunch of false positives due to probably-benign races. For example, RawLog_SetLastTime operates unprotected on global variables. This is questionable (since 'struct tm' is relatively large) and generates a TSAN warning. Fixing this to use a seqlock, or at least annotating it as benign, would be helpful for those trying to run glog in TSAN builds.

Another example is the thread-unsafe counters for LOG_EVERY_N and similar macros. These need to be annotated as benign.