Merge branch 'master' of https://github.com/bvanassche/fio

* 'master' of https://github.com/bvanassche/fio:
  Suppress uninteresting data race reports
  gettime: Rework the clock thread starting mechanism
  Improve Valgrind instrumentation of memory allocations
  Rename fio_mutex into fio_sem
  Split mutex.c and .h each into three files