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

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

- Use bus_{read,write}_*(9) instead of bus_space_{read,write}_*(9) etc
and take advantage of rman_get_rid(9) in order to save some softc
members.
- Provide and consume module dependency information for lebuffer(4).

o break newbus api: add a new argument of type driver_filter_t to
bus_setup_intr()

o add an int return code to all fast handlers

o retire INTR_FAST/IH_FAST

For more info: http://docs.freebsd.org/cgi/getmsg.cgi?fetch=465712+0+current/freebsd-current

Reviewed by: many
Approved by: re@

Add front-ends for the 'lebuffer' variants found on some SBus cards.
These are shared-memory variants based on Am79C90-compatible chips
that apart from the missing DMA engine are similar to the 'ledma'
variant including using a (pseudo-)bus/device for the buffer that
the actual LANCE device hangs off from. The performance of these is
close to that of the 'ledma' one, like expected at a few times the
CPU load though.