This patch adds support for executing multiple concurrent requests on
different devices on the same AHCI controller. The libdriver library
has been extended to include a generic multithreading interface, and
the AHCI driver has been extended to make use of this interface.
The original version of this code has been written by Arne Welzel.
This patch moves more includes (most of them, to tell the truth) to
common/include directory. This completes the list of includes needed
to compile current trunk with the new libc (but to do that you need
more patches in queue).
This patch also contains some modification (for compilation with new
headers) to the common includes under __NBSD_LIBC, the define used
in mk script to specialize compilation with new includes.
