nir: remove fnot/fxor/fand/for opcodes
There doesn't seem to be any reason to keep these opcodes around:
- fnot/fxor are not used at all.
- fand/for are only used in lower_alu_to_scalar, but easily replaced
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
There doesn't seem to be any reason to keep these opcodes around: