perf trace: Free thread_trace->files table

The fd->pathname table that is kept in 'struct thread_trace' and thus in
thread->priv must be freed when a thread is deleted.

This was also detected using -fsanitize=address.

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20230719202951.534582-6-acme@kernel.org


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