MFC r277300 (by smh): Mechanically convert cddl sun #ifdef's to illumos

Since the upstream for cddl code is now illumos not sun, mechanically
convert all sun #ifdef's to illumos #ifdef's which have been used in all
newer code for some time.

Also do a manual pass to correct the use if #ifdef comments as per style(9)
as well as few uses of #if defined(__FreeBSD__) vs #ifndef illumos.

MFC r258291: change the ioctl definition so that the fasttrap ioctl
handler is responsible for copying in userland data

MFC r258291: change the ioctl definition so that the fasttrap ioctl
handler is responsible for copying in userland data