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.

(Re)Enable -Werror=array-bounds.

enable -Wno-error=array-bounds for GCC 9 and hppa. machdep.c has a
bunch of warnings that i can't workaround yet.

- Determine KERN_AS automatically depending on whether OPT_MODULAR is
set or not, in the same way as libcompat.

- Specify OPT_MODULAR in the port Makefile instead of KERN_AS.

Now, KERN_AS=library is used for kernels without module(7) for all ports.

OK christos

branches: 1.5.16; 1.5.18;
spmath.o is an MD library, not an MD object.

Define ${LINKSCRIPT} in one place.

Use ${KERNLDSCRIPT}.

branches: 1.2.2;
Use LINKSCRIPT.

branches: 1.1.4; 1.1.6; 1.1.10;
Rename NetBSD/hp700 to NetBSD/hppa.

Unfortunately our VCS isn't very helpful here.

(Re)Enable -Werror=array-bounds.

enable -Wno-error=array-bounds for GCC 9 and hppa. machdep.c has a
bunch of warnings that i can't workaround yet.

- Determine KERN_AS automatically depending on whether OPT_MODULAR is
set or not, in the same way as libcompat.

- Specify OPT_MODULAR in the port Makefile instead of KERN_AS.

Now, KERN_AS=library is used for kernels without module(7) for all ports.

OK christos

branches: 1.5.16; 1.5.18;
spmath.o is an MD library, not an MD object.

Define ${LINKSCRIPT} in one place.

Use ${KERNLDSCRIPT}.

branches: 1.2.2;
Use LINKSCRIPT.

branches: 1.1.4; 1.1.6; 1.1.10;
Rename NetBSD/hp700 to NetBSD/hppa.

Unfortunately our VCS isn't very helpful here.

enable -Wno-error=array-bounds for GCC 9 and hppa. machdep.c has a
bunch of warnings that i can't workaround yet.

- Determine KERN_AS automatically depending on whether OPT_MODULAR is
set or not, in the same way as libcompat.

- Specify OPT_MODULAR in the port Makefile instead of KERN_AS.

Now, KERN_AS=library is used for kernels without module(7) for all ports.

OK christos

branches: 1.5.16; 1.5.18;
spmath.o is an MD library, not an MD object.

Define ${LINKSCRIPT} in one place.

Use ${KERNLDSCRIPT}.

branches: 1.2.2;
Use LINKSCRIPT.

branches: 1.1.4; 1.1.6; 1.1.10;
Rename NetBSD/hp700 to NetBSD/hppa.

Unfortunately our VCS isn't very helpful here.

- Determine KERN_AS automatically depending on whether OPT_MODULAR is
set or not, in the same way as libcompat.

- Specify OPT_MODULAR in the port Makefile instead of KERN_AS.

Now, KERN_AS=library is used for kernels without module(7) for all ports.

OK christos

branches: 1.5.16;
spmath.o is an MD library, not an MD object.

Define ${LINKSCRIPT} in one place.

Use ${KERNLDSCRIPT}.

branches: 1.2.2;
Use LINKSCRIPT.

branches: 1.1.4; 1.1.6; 1.1.10;
Rename NetBSD/hp700 to NetBSD/hppa.

Unfortunately our VCS isn't very helpful here.