Merge branch '3.4-maint'

* 3.4-maint:
  Clean up
  win32: Silence compiler warnings
  cleanup: Improve robustness when multiple cleanups run concurrently
  cleanup: Log size before cleaning
  Add x_try_unlink utility function
  test: Use helper functions instead of custom code
  test: Improve error messages from expect_{equal,different}_files

diff --cc doc/NEWS.adoc
Simple merge

diff --cc test/suites/pch.bash
Simple merge