Merge the [pgoyette-compat] branch

Rename min/max -> uimin/uimax for better honesty.

These functions are defined on unsigned int. The generic name
min/max should not silently truncate to 32 bits on 64-bit systems.
This is purely a n

Rename min/max -> uimin/uimax for better honesty.

These functions are defined on unsigned int. The generic name
min/max should not silently truncate to 32 bits on 64-bit systems.
This is purely a name change -- no functional change intended.

HOWEVER! Some subsystems have

#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))

even though our standard name for that is MIN/MAX. Although these
may invite multiple evaluation bugs, these do _not_ cause integer
truncation.

To avoid `fixing' these cases, I first changed the name in libkern,
and then compile-tested every file where min/max occurred in order to
confirm that it failed -- and thus confirm that nothing shadowed
min/max -- before changing it.

I have left a handful of bootloaders that are too annoying to
compile-test, and some dead code:

cobalt ews4800mips hp300 hppa ia64 luna68k vax
acorn32/if_ie.c (not included in any kernels)
macppc/if_gm.c (superseded by gem(4))

It should be easy to fix the fallout once identified -- this way of
doing things fails safe, and the goal here, after all, is to _avoid_
silent integer truncations, not introduce them.

Maybe one day we can reintroduce min/max as type-generic things that
never silently truncate. But we should avoid doing that for a while,
so that existing code has a chance to be detected by the compiler for
conversion to uimin/uimax without changing the semantics until we can
properly audit it all. (Who knows, maybe in some cases integer
truncation is actually intended!)

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Add comment to #ifdef - it's a long way from its original #if

Split the SYSV* compat code out into a separate compat_sysv module.

For monolithic kernels, both modules will be compiled as "built-ins",
while modular environments will be able to load the SYSVSEM,

Split the SYSV* compat code out into a separate compat_sysv module.

For monolithic kernels, both modules will be compiled as "built-ins",
while modular environments will be able to load the SYSVSEM, SYSVSHM,
and SYSVMSG code independant from the rest of compat.

This is a necessary precursor step to making the "STD" SYSV* code
into a separate module.

Tested in both monolithic and modular environments with no errors
seen.

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compile into nothing if not compat 50.

Provide compatibility for pre-christos-time_t sysv sysctls.