Better version of brf2, getting there with my understanding!  Think it needs some locking and to discard samples if it's too early.
Think I fixed brf2.c gives ~3Gb/s of entropy at ~30% fail after von neumann debiasing. Next I'll fold the changes in to brf_entropy and do a release!
brf_entropy now uses bladerf_stream(), 20MB/s without optimisation.
no changes to rtl_entropy
Time for a release!
whoops, missed testing the Daemon mode, fixed now!
In non-encryption mode, write out not the old buffer but the buffer that
contains the entropy we just collected. Writing out the old buffer made
the output a little bit too predictable:

  $ rtl-entropy 2>/dev/null | xxd | head
  0000000: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000010: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000020: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000030: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000040: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000050: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000060: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................