perf buildid-cache: Do not require purge files to also be in the file system

perf buildid-cache: Do not require purge files to also be in the file system

realname() returns NULL if the file is not in the file system, but we can
still remove it from the build ID cache in that case, so continue and
attempt the purge with the name provided.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-10-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>