- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r263289: Update NetBSD Foundation copyrights to 2-clause BSD

The NetBSD Foundation states "Third parties are encouraged to change the
license on any files which have a 4-clause license contributed to the
NetBSD Foundation to a 2-clause license."

This change removes clauses 3 and 4 from copyright / license blocks that
list The NetBSD Foundation as the only copyright holder.

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

Merge from vmobj-rwlock branch:
Remove unused inclusion of vm/vm_pager.h and vm/vnode_pager.h.

Sponsored by: EMC / Isilon storage division
Tested by: pho
Reviewed by: alc

Fix build on 32-bit systems.

After switching mutexes to use lwsync, they no longer provide sufficient
guarantees on acquire for the tlbie mutex. Conversely, the TLB invalidation
sequence provides guarantees that do not need to be redundantly applied on
release. Roll a small custom lock that is just right. Simultaneously,
convert the SLB tree changes back to lwsync, as changing them to sync
was a misdiagnosis of the tlbie barrier problem this commit actually fixes.

Execute an initial ptesync if and only if the PTE is actually being
invalidated, as opposed to a ref/changed bit update.

More PMAP performance improvements: skip 256 MB segments entirely if they
are are not mapped during ranged operations and reduce the scope of the
tlbie lock only to the actual tlbie instruction instead of the entire
sequence. There are a few more optimization possibilities here as well.

More PMAP performance improvements: on powerpc64, when TLBIE can be run
with exceptions enabled, leave them enabled and use a regular mutex to
guard TLB invalidations instead of a spinlock.

Remove some dead code: unnecessary isyncs and memory sorting, which are
handled in mtmsr() and mem_regions(), respectively.

Only keep track of PTE validity statistics for pages not locked in the
table. The 'locked' attribute is used to circumvent the regular page table
locking for some special pages, with the result that including locked pages
here causes races when updating the stats.

Add some isync()s related to the 64-bit MMU scratch page to avoid race
conditions on its invalidation.

Add an abstraction layer to the 64-bit AIM MMU's page table manipulation
logic to support modifying the page table through a hypervisor. This
uses KOBJ inheritance to provide subclasses of the base 64-bit AIM MMU
class with additional methods for page table manipulation.

Many thanks to Peter Grehan for suggesting this design and implementing
the MMU KOBJ inheritance mechanism.