perf trace: Fix non-listed archs in the syscalltbl routines

This fixes a build breakage on 32-bit arm, where the
syscalltbl__id_at_idx() function was missing.

Committer notes:

Generating a proper syscall table from a copy of
arch/arm/tools/syscall.tbl ends up being too big a patch for this rc
stage, I started doing it but while testing noticed some other problems
with using BPF to collect pointer args on arm7 (32-bit) will maybe
continue trying to make it work on the next cycle...

Fixes: 7a2fb561 ("perf trace: Fix iteration of syscall ids in syscalltbl->entries")
Suggested-by: Howard Chu <howardchu95@gmail.com>
Signed-off-by:  <jslaby@suse.cz>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/lkml/3a592835-a14f-40be-8961-c0cee7720a94@kernel.org


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