merge fixes from the master-appio-fix branch

[Vince Weaver]

These fixes prevent appio from instrumenting PAPI itself which can lead to problems.

The fix is intrusive and renames the ->read and ->write methods for the PAPI-C interface, changing the component API/ABI and breaking any external components.

[Giuseppe Congiu]

@Vince Weaver can you provide a bit more context about this one? Thanks