perf tools: Make has_kcore_dir() work also for guest kcore_dir

perf tools: Make has_kcore_dir() work also for guest kcore_dir

Copies of /proc/kallsyms, /proc/modules and an extract of /proc/kcore can
be stored in the perf.data output directory under the subdirectory named
kcore_dir. Guest machines will have their files also under subdirectories
beginning kcore_dir__ followed by the machine pid. Make has_kcore_dir()
return true also if there is a guest machine kcore_dir.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-22-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>