MFC r266773,r280680,r311710:

r266773 (by jhb):

Fix a couple of size_t != int warnings.

r280680 (by kevlo):

Print size_t's with %zu rather than "%zd.

r311710:

Style fixes

- Delete trailing whitespace
- Use nitems(mib) instead of hardcoding the mib length

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 r265267:

Fix width/alignment of JID column. Make it support up to the maximum 7-wide
JIDs. On a system using jails for common tasks the JID can quickly increase.

MFC r265249,r265250,r265251:

- Add -J command/flag to filter by jail name/jid. This will automatically
display the JID as well (the -j command/flag).
- Add a hint for 'u' and 'J' command that '+' displays all.
- Add J command to help.

MFC r265267:

Fix width/alignment of JID column. Make it support up to the maximum 7-wide
JIDs. On a system using jails for common tasks the JID can quickly increase.

MFC r265249,r265250,r265251:

- Add -J command/flag to filter by jail name/jid. This will automatically
display the JID as well (the -j command/flag).
- Add a hint for 'u' and 'J' command that '+' displays all.
- Add J command to help.