ACPI update

[Alexander Polakov]

 I am working on updating ACPI to modern state and ACPI interrupt
 routing. You can get the current code here [1]. It's going not bad but
 I have some questions which I need answers for before moving on.

 1) Locking. I have no idea which one should be used. There're 2
 families of locking macros: ACPI_SERIAL_* and ACPI_LOCK_*
 (see sys/dev/acpica5/acpivar.h). FreeBSD uses mtx_* for ACPI_LOCK
 and sx_* for ACPI_SERIAL.

 2) APIC. Current APIC code doesn't allow setting interrupts from other
 subsystems and changing interrupts after boot, but this is required for
 BUS_CONFIG_INTR to work.

 [1] http://gitweb.dragonflybsd.org/~polachok/dragonfly.git/newacpi