libsubcmd: Avoid SEGV/use-after-free when commands aren't excluded

The array shortening may perform unnecessary array copies.

Before commit 657a3efe ("lib subcmd: Avoid memory leak in
exclude_cmds") this was benign, but afterwards this could lead to a
SEGV.

Fixes: 657a3efe ("lib subcmd: Avoid memory leak in exclude_cmds")
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Chenyuan Mi <cymi20@fudan.edu.cn>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230707230926.841086-1-irogers@google.com


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