perf bpf: Add missing xyarray.h header

This was being obtained indirectly via evsel.h -> counts.h, since we
don't need xyarray in counts.h, we need to add it here explicitely
before removing it from counts.h.

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-jirmxg527i82yz31bwad9we7@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>