[libre-riscv-dev] morphing 6600 code to use power decoder

[Luke Kenneth Casson Leighton]

this is excruciatingly slow work. i've only just got 4 out-of-order
instructions (2 per Function Unit) operational again after changing to
use multi-control signals on the register file: one each for each
port.

that's still not out of the woods, yet: the last time i did this it
took hundreds of runs of random operations to be partially confident
of an operational OoO design.

i still have LD/ST and branch to put back in.

l.