lint: suppress "used but not defined" for bin, sbin, usr.bin, usr.sbin

These diagnostics are emitted by lint2, and like all diagnostics from
lint2, they don't affect the exit status.

In libc, lint cannot handle the renamings from namespace.h, generating
many false positive diagnostics since 'libc_function' is used but
'_libc_function' is defined. Until this situation is handled properly,
suppress this diagnostic.

{usr.,}{s,}bin: replace LINT_SUPPORTED with the standard NOLINT

While here, re-enable lint in those cases where lint was skipped due to
a bug in interpreting abstract types, which was fixed in cgram.y 1.469
from 2023-08-02.

usr.bin: enable lint checks for most programs in /usr/bin

Previously, lint was only activated for the libraries, but not for the
kernel or userland programs. Activate lint for the programs in /usr/bin
for now, more will follow later.

This only affects builds that set MKLINT=yes.

Default to WARNS=5

branches: 1.9.6;
Enable WARNS=4 by default for usr.bin, except for:
awk bdes checknr compile_et error gss hxtool kgetcred kinit
klist ldd less lex locale login m4 man menuc mk_cmds
mklocale msgc openssl rpcgen rpcinfo sdiff spell ssh
string2key telnet tn3270 verify_krb5_conf xlint

branches: 1.8.26;
WFORMAT is no more...

Fix indentation..

More format string cleanup by sommerfeld.

branches: 1.5.4; 1.5.12;
WARNS=1 is now the default for usr.bin! Thanks to mrg for assistance -- lukem

merge lite2 changes (just SCCS ids)

RCS ID police

Add RCS indentifiers.

branches: 1.1.1;
Initial revision