Revisit initial SID name mapping

[pebenito]

The binary policy does not have the initial SID<->name mapping. Revisit how this is remapped.

[pebenito]

It is currently a static mapping in policy_extend.c:

static const char *const sidnames[] = {
    "undefined",
    "kernel",
    "security",
    "unlabeled",
    "fs",
    "file",
    "file_labels",
    "init",
    "any_socket",
    "port",
    "netif",
    "netmsg",
    "node",
    "igmp_packet",
    "icmp_socket",
    "tcp_socket",
    "sysctl_modprobe",
    "sysctl",
    "sysctl_fs",
    "sysctl_kernel",
    "sysctl_net",
    "sysctl_net_unix",
    "sysctl_vm",
    "sysctl_dev",
    "kmod",
    "policy",
    "scmp_packet",
    "devnull"
};

These names are applied in code below this struct definition (if the names are missing). Consider trying to pull in kernel headers or policy headers as an alternative.