perf trace: Make syscall table stable

Namhyung fixed the syscall table being reallocated and moving by
reloading the system call pointer after a move:
https://lore.kernel.org/lkml/Z9YHCzINiu4uBQ8B@google.com/


This could be brittle so this patch changes the syscall table to be an
array of pointers of "struct syscall" that don't move. Remove
unnecessary copies and searches with this change.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: https://lore.kernel.org/r/20250319050741.269828-13-irogers@google.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>