Enforce -Wmissing-prototypes -Wstrict-prototypes for all ppc ports.
Split out macppc cpu support and make common to mpc6xx ports. Make
other mpc6xx ports use it. Add evcnts for mpc6xx traps.
pci_attach_args *" instead of from four separate parameters which in
all cases were extracted from the same "struct pci_attach_args".
This both simplifies the driver api, and allows for alternate PCI
interrupt mapping schemes, such as one using the tables described in
the Intel Multiprocessor Spec which describe interrupt wirings for
devices behind pci-pci bridges based on the device's location rather
the bridge's location.
Tested on alpha and i386; welcome to 1.5Q
