MFC r254813,259587: Rename the kld_unload event handler to kld_unload_try
MFC r257152: Do some cleanup of the SDT code
MFC r257417:  Remove references to an unused fasttrap probe hook
MFC r257679: Use suword32 and suword64 instead of copyout(9) in fasttrap
MFC r258291: change the ioctl definition so that the fasttrap ioctl
handler is responsible for copying in userland data