perf trace beauty: renameat's newdirfd may also be AT_FDCWD

Noticed while working on renameat2.

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-8omchrcjcvlwoxxv6wrjehfh@git.kernel.org


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