Merge r256868,257276-257277,257515,257913 from head. These are fixes
required to make Xen buildable w/o INET.  This is the same as r259541
in stable/10 by glebius.
Generate *all* the needed autogenerated header files.  For some reason
normal builds still work without this, but "make universe" requires it.

Tested with "make universe".

This is a direct commit to stable/9 because this module does not exist
in head or stable/10.