identification (e.g. isa:0x3f0 or pci0:2:1:0). In libbus,
the device is turned into a path name. For bus_space_map(),
the resource is now specified in a second argument.
Before:
bus.map('/dev/proto/pci0:2:1:0/pcicfg')
busdma.tag_create('/dev/proto/pci0:2:1:0/busdma', ...)
Now:
bus.map('pci0:2:1:0', 'pcicfg')
busdma.tag_create('pci0:2:1:0', ...)
While here:
1. have the Python bindings contain constants for the space
identifiers and the sync operation.
2. change the segment iterators to return None when done,
not ENXIO.
