MFC r261719:
Fix wrong device name in example.

PR:             docs/185602
Submitted by:   koitsu
MFC r252895: Add a man page for the SDT_* macros
MFC r253720: Use kern_ioctl() rather than ioctl() for testing the FBT provider
MFC r254468,r254469: Add a "translated type" argument to SDT_PROBE_ARGTYPE()

Note: this breaks ABI compatibility with older modules with SDT probes.

My opinion is that benefits outweigh downsides, because I am not aware
of any thirdparty binary-only modules with SDT probes.
MFC r254810: Remove the kld lock macros and just use the sx(9) API
MFC r254811: call linker_file_lookup_set() with the shared lock held
MFC r255776: Give argtype struct names a different prefix than probe
struct names
MFC r255777: Omit "__restrict" when generating syscall argument strings

syscall argument strings are also regenerated as part of this commit
MFC r257143: Fix a couple of bugs in the fasttrap emulation of a "push
%rbp" instruction
MFC r254266,254309: Add event handlers for module load and unload events

This is just a merge of EVENTHANDLER.9, the actual code chnage was merged earlier.
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
MFC r252850: Hide references to mod_lock
MFC r256148: Initialize and free the DTrace taskqueue in the dtrace
module load/unload handlers
MFC r260132: Allocate the probe ID unrhdr before the DTrace kld_* event
handlers are registered
MFC r255971: Fix some typos that were causing probe argument types to
show up as unknown

MFC slacker:	markj
MFC r258622,258675: dtrace sdt: remove the ugly sname parameter of
SDT_PROBE_DEFINE