Merge branch '3.3-maint'

Merge branch '3.3-maint'

* 3.3-maint:
  Update NEWS
  Don't skip compiler argument following AFFECTS_CPP without TAKES_ARG
  Clean up
  Clean up redundant expression
  -fdebug-prefix-map is supported in clang 3.8 and newer
  Fix leaked file descriptor
  Clang emits warnings for unused linker arguments, respect that!
  doc: Improve markup
  Add some fallthrough comments to work around GCC compiler warnings