A free function called via UFCS (recv.fn(args)) whose first param is *T
was passed the receiver by value (LLVM "Call parameter type does not
match function signature"), and a function reached only via UFCS was
declared but never emitted (undefined symbol at link).
The bare-name UFCS fallback now mirrors the qualified-method path: it
lazily lowers the target body and calls fixupMethodReceiver +
coerceCallArgs, so the value receiver gets the same implicit address-of
as a struct-defined method and mutations through *T are visible.
Regression: 0039-basic-free-fn-ufcs-pointer-receiver.sx.
