libct: fixStdioPermissions: skip chown if not needed
libct: fixStdioPermissions: skip chown if not needed

Since we already called fstat, we know the current file uid. In case it
is the same as the one we want it to be, there's no point in trying
chown.

Remove the specific /dev/null check, as the above also covers it
(comparing /dev/null uid with itself is true).

This also fixes runc exec with read-only /dev for root user.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kolyshkin/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,kolyshkin/runc,opencontainers/runc