Ceph » Messengers

On Linux the definition of a sockaddr is:
```
struct sockaddr {
sa_family_t sa_family;
char sa_data<sup>14</sup>;
}
```
And on FreeBSD ik looks like:
```
struct sockaddr {
unsigned char sa_len; /* total length /
sa_family_t sa_family; / address family /
char sa_data<sup>14</sup>; / actually longer; address value */
};
```

We need to do 2 things:
- maintain the sa_len value for FreeBSD, otherwise memcmp() calls
can return unequal, where the only difference would be `sa_len`.
sa_len is set on returns from the FreeBSD syscalls.
- Look into comparing structures whch have sockaddr as members.

Testing with `ceph_test_msgr` will show all poll tests failing.
Most of the time the script wil just loop endlessly.

Future work could be to actually rework the comparission routines in
msg_types.h to make full use of the structure. But for now it looks
like it not needed.