MFC r271197:
Add more bits for the XSAVE features from CPUID 0xd, sub-function 1
%eax report.  Print the XSAVE features 0xd/1 in the boot banner.
MFC r271206:
Adjust the definition of struct xstate_hdr according to SDM rev. 50.
MFC r271208:
Add a define for index of IA32_XSS MSR.
MFC: r272492

  Merge pc98's machdep.c into i386/i386/machdep.c.
MFC r275842: Do not count RCTD bit set as an error.

We can not really implement it, but specification tells that it "shall"
work, so it can be safely ignored.
MFC r275958: Report XML parsing errors.
MFC r275959: Report initiator id in portlist XML in more formalized way.
MFC r273087 (with modifications):
  Overhaul if_gif(4):
   o convert to if_transmit;
   o use rmlock to protect access to gif_softc;
   o use sx lock to protect from concurrent ioctls;
   o remove a lot of unneeded and duplicated code;
   o remove cached route support (it won't work with concurrent io);
   o style fixes.

MFC r273090:
  Move memset under ifdef INET6.

MFC r273091:
  Add more ifdefs. SIOC*_IN6 are defined only with INET6.

MFC r273121:
  Add inet/inet6 to the dependency list. Without them if_gif is useless.

MFC r273209 by bz:
  After r273087,r273090,r273091,r273121 changes to gif(4) try to fix
  NOIP builds for real.

MFC r273587:
  Remove redundant check and m_pullup() call.