Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

This needs to be done manually because if the irq() routine is
implemented then we want something like "nic->irqno = pci->irqno;",
else we do "nic->irqno = 0;" nic->ioaddr may also need to be set
carefully.

Also added local variables to end of many files, for emacs indentation
to match kernel style (tab does 8 space indent).

ISA 3c509 is currently non-functional, although the EISA (3c509-eisa) and
MCA (3c529) variants should build OK.

None of this code is yet tested.

perl -pi -0777 -e 's/^static struct \w+_driver (\w+) =\s*(\w+_DRIVER \()/${2} ${1},/msg' *.c

Probe mechanisms now use standard EISA and MCA bus methods, with 3c509.c
defining a custom ISA bus to handle the 3c509 contention resolution logic.