MFC r254265:
 Make sure bootonly.iso for -BETAs and -RCs use the releases/
 directory on the FTP mirrors to fetch distributions, since
 these are always pushed to releases/ during the release cycle.
MFC r254092:
  Make the check for number of entries less strict.
  Some partitioning tools can create GPT with number of entries less
  than 128.
MFC r254008 Make the fallback from MSIX to MSI interrupt usage more graceful.
MFC r254262  Further improve the msix setup, make sure pci_alloc_msix() gives us
             the vectors we requested, and fall back to MSI when not, also release
             any allocated resources before the fallback.
MFC r254264  Make the igb_mq_start() routine use TRYLOCK rather than simple
             queuing, there were latency and other problems with the latter.
Merge remote-tracking branch 'upstream-github/stable/9' into stable/9