Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Switch to C99 exact-width types.

/* -> /*- for copyright notices, minor format tweaks as necessary

Fix last second typo.

Use ffs(x) == popcnt(x ^ (x - 1)) to implement 64 bit ffsl(). gcc's
ffs() builtin uses this already but truncates the upper 32 bits.

Move the "- 1" into the RQB_FFS(mask) macro itself so that
implementations can provide a base zero ffs function if they wish.
This changes
#define RQB_FFS(mask) (ffs64(mask))
foo = RQB_FFS(mask) - 1;
to
#define RQB_FFS(mask) (ffs64(mask) - 1)
foo = RQB_FFS(mask);
On some platforms we can get the "- 1" for free, eg: those that use the
C code for ffs64().

Reviewed by: jake (in principle)

Make the run queue parameters machine dependent. Optimize 64 bit
architectures by using a 64 bit word for the bit array which keeps
track of non-empty queues.

Reviewed by: peter