- 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)

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

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

Expand the set of APIs available for locating PCI capabilities:
- pci_find_extcap() is repurposed to be used for fetching PCI-express
extended capabilities (PCIZ_* constants in <dev/pci/pcireg.h>).
- pci_find_htcap() can be used to locate a specific HyperTransport
capability (PCIM_HTCAP_* constants in <dev/pci/pcireg.h>).
- Cache the starting location of the PCI-express capability for PCI-express
devices in PCI device ivars.

Do a sweep of the tree replacing calls to pci_find_extcap() with calls to
pci_find_cap() instead.

Move the hostb driver out of the i386 and amd64 PCI code (where it was
duplicated anyways) and into a single MI driver. Extend the driver a bit
to implement the bus and PCI kobj interfaces such that other drivers can
attach to it and transparently act as if their parent device is the PCI
bus (for the most part).