introduce new GCC 12 warning disables and use them in a few places

this introduces 4 new warning disable flags:

CC_WNO_MISSING_TEMPLATE_KEYWORD
CC_WNO_REGISTER
CC_WNO_STRINGOP_OVERREAD

introduce new GCC 12 warning disables and use them in a few places

this introduces 4 new warning disable flags:

CC_WNO_MISSING_TEMPLATE_KEYWORD
CC_WNO_REGISTER
CC_WNO_STRINGOP_OVERREAD
CC_WNO_ARRAY_BOUNDS

and documents them in README.warnings. of these, the string op
and array bounds are both problematic (real bugs) and also spurious
(not real bugs), and the other 2 are mostly temporary for older
3rd party code.

add some new uses of CC_WNO_STRINGOP_OVERFLOW.

fix m68k build for gallium and GCC 12.

show more ...

install prenice(1) and man page links.

Fix sign-compare issues

WARNS=3 and remove default values.

pgrep and pkill: search the process table for processes with a particular
set of characteristics, and either print or signal the matching set. Mostly
compatible with the Solaris commands of the same

pgrep and pkill: search the process table for processes with a particular
set of characteristics, and either print or signal the matching set. Mostly
compatible with the Solaris commands of the same name.

show more ...