resource allocation on x86 platforms:
- Add a new helper API that Host-PCI bridge drivers can use to restrict
  resource allocation requests to a set of address ranges for different
  resource types.
- For the ACPI Host-PCI bridge driver, use Producer address range resources
  in _CRS to enumerate valid address ranges for a given Host-PCI bridge.
  This can be disabled by including "hostres" in the debug.acpi.disabled
  tunable.
- For the MPTable Host-PCI bridge driver, use entries in the extended
  MPTable to determine the valid address ranges for a given Host-PCI
  bridge.  This required adding code to parse extended table entries.

Similar to the new PCI-PCI bridge driver, these changes are only enabled
if the NEW_PCIB kernel option is enabled (which is enabled by default on
amd64 and i386).

Approved by:	re (kib)