[ppc] os::print_function_and_library_name shall resolve function descriptors transparently

When function descriptors are fed to os::print_function_and_library_name() to get debug output, it would be very helpful to transparently handle the case where the address is not a code pointer but a function descriptor.

Of the official OpenJDK platforms this affects only ppc, but also includes at least ia64 for those who maintain ports to that platform.

Fixing this will also fix the display of signal handlers on linux ppc which still show up without function names after JDK-8258606.