Import OpenBSD 4.9 and make the current L4 port reflect the changes.

Important changes affecting the L4 port include:

 - ci_cpuid converts from 32 bits to uint64_t
 - netisrs are handled as generic softintrs at IPL_SOFTNET
 - evcount_intr for evcount_attach() is gone for good
 - PCIe support (which is not ported yet)

For a more complete list of changes, visit:

  http://www.openbsd.org/plus49.html