parse-opcodes outdated

[takeBrian]

Kindly look into the version of the riscv-opcodes repo that is downloaded by running the git recursive update for rocket-tools; this version of riscv-opcodes seems to be outdated, and running its parse-opcodes script broke the previously working builds of some of the other tools downloaded by rocket-tools automatically.

[ZenithalHourlyRate]

May get fixed by c17f76b