[perfmon2] Improving the the libpfm compatibility between shared library version

Hi, I have been using abidiff (https://fedoraproject.org/wiki/How_to_check_for_ABI_changes_with_abidiff) to view the changes in the libpfm shared library interface. The attached libpfm_changes.log show the detailed changes between libpfm-4.6 and libpfm-4.7. One thing that is concerning is the ch

[perfmon2] [PATCH] Hide internal functions and variables from external view

The shared library should only make the functions and variable visible that are actually part of the interfaces to the outside world. Anything that is visible to the outside could potentially be used (or abused) by code linking with the library. Making the internal functions and variables hidden g