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