CL 298669 implemented wrapping for defer/go calls so the function
being called with defer or go statement has no arguments. This
simplifies the compiler and the runtime, especially with the
new ABI.
Currently, it does not wrap functions that has no arguments but
only results. For defer/go calls, the results are not used. But
the runtime needs to allocate stack space for the callee to store
the results. Wrapping functions with results makes the runtime
simpler.
TODO: maybe not wrap if all results are in registers.