rts: drop interpretBCO support from non-dyn ways on wasm

This commit drops interpretBCO support from non dynamic rts ways on
wasm. The bytecode interpreter is only useful when the RTS linker also
works, and on wasm it only works for dynamic ways anyway. An
additional benefit of dropping interpretBCO is reduction in code size
of linked wasm modules, especially since interpretBCO references
ffi_call which is an auto-generated large function in libffi-wasm and
unused by most user applications.