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

Use sysctl kern.sched.cpusetsize to retrieve size of kernel cpuset.

Check small set and reject it, this is how kernel did. Always use the
size kernel is using.

- Revert r214409.
- Use long word to figure out sizeof kernel cpuset, hope it works.

Fix typo.

Get cpuset in pthread_attr_get_np() and free it in pthread_attr_destroy().

MFC after: 7 days

Convert thread list lock from mutex to rwlock.

Avoid various shadowed variables. libthr is now almost WARNS=4 clean except
for some const dequalifiers that needs more careful investigation.

Ok'ed by: davidxu

Compile libthr with warnings.

Fix a bug when calculating remnant size.

Check actual size of cpuset kernel is using and define underscore version
of API.

implement pthread_attr_getaffinity_np and pthread_attr_setaffinity_np.

Remove 3rd clause, renumber, ok per email

Use kernel facilities to support real-time scheduling.

- Use same priority range returned by kernel's sched_get_priority_min()
and sched_get_priority_max() syscalls.
- Remove unused fields from structure pthread_attr.

WARNS level 4 cleanup.

Return real detached state.

Import my recent 1:1 threading working. some features improved includes:
1. fast simple type mutex.
2. __thread tls works.
3. asynchronous cancellation works ( using signal ).
4. thread synchronization is fully based on umtx, mainly, condition
variable and other synchronization objects were rewritten by using
umtx directly. those objects can be shared between processes via
shared memory, it has to change ABI which does not happen yet.
5. default stack size is increased to 1M on 32 bits platform, 2M for
64 bits platform.
As the result, some mysql super-smack benchmarks show performance is
improved massivly.

Okayed by: jeff, mtm, rwatson, scottl

Move the weak references to the top of the file to conform
to the format of other similar files in libthr.

- Add libthr but don't hook it up to the regular build yet. This is an
adaptation of libc_r for the thr system call interface. This is beta
quality code.