Warning about struct/class thread_counters

[eschnett]

I see the following warning when building HPX:

/project/projectdirs/m152/schnette/hopper/SIMFACTORY/hpx-master/src/hpx-master/hpx/components/papi/server/papi.hpp:155:16: warning: class 'thread_counters' was previously declared as a struct [-Wmismatched-tags]
        friend class thread_counters;
               ^
/project/projectdirs/m152/schnette/hopper/SIMFACTORY/hpx-master/src/hpx-master/hpx/components/papi/server/papi.hpp:72:12: note: previous use is here
    struct thread_counters
           ^
/project/projectdirs/m152/schnette/hopper/SIMFACTORY/hpx-master/src/hpx-master/hpx/components/papi/server/papi.hpp:155:16: note: did you mean struct here?
        friend class thread_counters;
               ^~~~~
               struct

[hkaiser]

This was fixed by 733a374