It is getting this via evsel.h, that don't strictly need counts.h, just
forward declarations for some structs, so add it here before we remove
it from there.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-jwcbm9gv9llloe3he5qkdefs@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>