MFC r309676

Export the whole thread name in kinfo_proc

kinfo_proc::ki_tdname is three characters shorter than
thread::td_name. Add a ki_moretdname field for these three
extra characters. Add the new field to kinfo_proc32, as well.
Update all in-tree consumers to read the new field and assemble
the full name, except for lldb's HostThreadFreeBSD.cpp, which
I will handle separately. Bump __FreeBSD_version.

Sponsored by: Dell EMC

MFC 281266:
Move the 32-bit compatible procfs types from freebsd32.h to <sys/procfs.h>
and export them to userland.
- Define __HAVE_REG32 on platforms that define a reg32 structure and check
for this in <sys/procfs.h> to control when to export prstatus32, etc.
- Add prstatus32_t and prpsinfo32_t typedefs for the 32-bit structures.
libbfd looks for these types, and having them fixes 'gcore' in gdb of a
32-bit process on a 64-bit platform.
- Use the structure definitions from <sys/procfs.h> in gcore's elf32 core
dump code instead of duplicating the definitions.

Merge reaper facility.

MFC r270443 (by mjg):
Properly reparent traced processes when the tracer dies.

MFC r273452 (by mjg):
Plug unnecessary PRS_NEW check in kern_procctl.

MFC 275800:
Add a facility for non-init process to declare itself the reaper of
the orphaned descendants.

MFC r275821:
Add missed break.

MFC r275846 (by mckusick):
Add some additional clarification and fix a few gammer nits.

MFC r275847 (by bdrewery):
Bump Dd for r275846.

MFC r258661:
Add sysctl KERN_PROC_SIGTRAMP to retrieve signal trampoline location for the
given process.

Approved by: re (gjb)

MFC 281266:
Move the 32-bit compatible procfs types from freebsd32.h to <sys/procfs.h>
and export them to userland.
- Define __HAVE_REG32 on platforms that define a reg32 structure and check
for this in <sys/procfs.h> to control when to export prstatus32, etc.
- Add prstatus32_t and prpsinfo32_t typedefs for the 32-bit structures.
libbfd looks for these types, and having them fixes 'gcore' in gdb of a
32-bit process on a 64-bit platform.
- Use the structure definitions from <sys/procfs.h> in gcore's elf32 core
dump code instead of duplicating the definitions.

Merge reaper facility.

MFC r270443 (by mjg):
Properly reparent traced processes when the tracer dies.

MFC r273452 (by mjg):
Plug unnecessary PRS_NEW check in kern_procctl.

MFC 275800:
Add a facility for non-init process to declare itself the reaper of
the orphaned descendants.

MFC r275821:
Add missed break.

MFC r275846 (by mckusick):
Add some additional clarification and fix a few gammer nits.

MFC r275847 (by bdrewery):
Bump Dd for r275846.

MFC r258661:
Add sysctl KERN_PROC_SIGTRAMP to retrieve signal trampoline location for the
given process.

Approved by: re (gjb)