cfc2 and ctc2 aren't implemented in LLVM's assembler

[ayrtonm]

For some reason the mips assembler only implements instructions for moving between the general purpose registers and the data registers of cop2 (mfc2 and mtc2), but not for the control registers of cop2 (cfc2 and ctc2). This means that registers r32-r63 of the GTE (including all the matrix registers) aren't usable.

This could be fixed in llvm. On the other hand, GTE commands are custom to the playstation so it'll probably be necessary to make something like the rust-psp vfpu assembler anyway so the instructions could also be added there.