Merge branch 'anon-fault'

Merge page fault engine from Nico:

"This series introduces a new page_fault ioengine for Anonymous memory
  testing. This enables using fio’s existing framework and job files for
  memory management style workloads without relying on a filesystem. An
  example job file is included to demonstrate usage and lays the
  groundwork for how we plan on utilizing fio to test a number of MM
  related workloads."

* anon-fault:
  engines/page_fault: minor style cleanups
  Documentation: update the documentation to include the page_fault engine
  page_fault: add mmap-backed ioengine for anonymous faults