Ruamoko and v6(p) have their own copies despite being (currently) the
same, and spir-v's is currently empty, but now targeting spir-v doesn't
try to emit ruamoko code.
Simple functions now get to the code-gen phase (where they fail since
it's the wrong for other reasons). Parameter types aren't right for
spir-v yet as non-const params need to be references.
I'd gotten tired of all the convoluted progs version checks, and with
the addition of spirv, they're not even always relevant, and adding C
(when I get to it) will make things even worse. However, for now the
first victim is just the parameter/return value size check.