MFC r303929,r303930,r303931,r303932,r303933:

  r303929:
    Fix -S with -b not atomically updating the destination file.
  r303930:
    Support -v for -l.
  r303931:
    Fix -S with -l not being atomic.
  r303932:
    Fix -b failure not restoring flags on the destination file.
  r303933:
    Squelch a false-positive Clang static analyzer warning.