Don't force 64-bit DWARF2 on MIPS

64-bit debug data is only necessary for objects with greater than 4GB of
debug data, and is not used on other 64-bit FreeBSD targets.

Sponsored by:	DARPA, AFRL
Allow kernels without options SOFTUPDATES to build.  This should fix the
embedded tinderboxes.

Reviewed by:	emaste
MFP4: 223121 (FDT infrastructure portion)

Implement support for interrupt-parent nodes in simplebus.  The current
implementation requires that device declarations have an interrupt-parent
node and that it point to a device that has registered itself as a
interrupt controller in fdt_ic_list_head and implements the fdt_ic
interface.

Sponsored by:   DARPA/AFRL
Add comments that taskqueue_enqueue_locked() returns without the lock.