Merge tag 'pidfd-fixes-v5.2-rc4' of

Pull pidfd fixes from Christian Brauner:
 "The contains two small patches to the pidfd samples and test binaries

  They were lacking appropriate ifdefines for __NR_pidfd_send_signal and
  could hence lead to compilation errors when that was not defined.

  This was spotted on mips independently by Guenter Roeck (who was kind
  enough to send a fix for the samples binary) and Arnd who spotted it
  in linux-next.

  Apart from these two patches, there's also a patch to update the
  comments for the pidfd_send_signal() syscall which were slightly
  wrong/inconsistenly worded"

* tag 'pidfd-fixes-v5.2-rc4' of
  tests: fix pidfd-test compilation
  signal: improve comments
  samples: fix pidfd-metadata compilation