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

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

Merge revision 1.5 from NetBSD: Fix a typo in a comment.
NetBSD rev. 1.4 (addition of the OFW_PCI_PHYS_HI_BUS macro) had already
been merged prior to adding this file to FreeBSD (with the 1.3 tag though).

1. Add ofw_pci.h with definitions for the OpenFirmware PCI bindings
2. Add OF_getprop_alloc(), a helper function that will malloc() a sufficient
amount of memory and then retrieve a property value into it.

Approved by: benno
Obtained from: NetBSD (1)