kdump(8): Add more support for printing flag etc. names.
* New support for: eaccess() modes, faccessat() modes and atflag,
fchmodat() atflag, fchownat() atflag, fstatat() atflag,
linkat() atflag, unlinkat() atflag, utimensat() atflag,
getvfsstat() flags, lchflags() flags, chflagsat() flags and atflag,
kenv() actions, usched_set() commands, sys_checkpoint() types,
procctl() commands, mountctl() operations, and varsym_{list,set}()
levels.
* Fix flags printing in chflags() and fchflags().
* Better separate mount() and getfsstat() flags definitions.
* Adjust grepping for fcntl() commands send/recvmsg() etc. flags to
include flags with more than one underscore in their name, like
F_DUPFD_CLOEXEC.
Still missing: extexit()'s 'how' argument.