This is another old gomp4 patch that demotes an ICE in PR71959 to a
linker warning. One problem here is that it is not clear if OpenACC
allows individual member functions in C++ classes to be marked as acc
routines. There's another issue accessing member data inside offloaded
regions. We'll add some support for member data OpenACC 2.6, but some of
the OpenACC C++ semantics are still unclear.

Is this OK for trunk? I bootstrapped and regtested it for x86_64 Linux
with nvptx offloading.

Thanks,
Cesar