perf beauty socket/prctl_option: Cope with extended regexp complaint by grep

perf beauty socket/prctl_option: Cope with extended regexp complaint by grep

Noticed on fedora 38, the extended regexp that so far was ok for both
grep and sed now gets complaints by grep, that says '/' doesn't need to
be escaped with '\'.

So stop using '/' in sed, use '%' instead and remove the \ before / in
the common extended regexp.

Link: https://x.com/SMT_Solvers/status/1710380010098344192?s=20
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/ZUEddFPTJHVLhH%2F6@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>