Consistently handle 2nd and 3rd arguments of [gs]etsockopt as unsigned

Consistently handle 2nd and 3rd arguments of [gs]etsockopt as unsigned

The second (level) and third (optname) arguments of getsockopt and
setsockopt syscalls are enums, so treat them consistently as enums:
use "unsigned int" type to avoid potential sign extension issues.

* net.c (print_sockopt_fd_level_name, print_getsockopt,
print_setsockopt): Change type of "level" and "name" arguments
from "int" to "unsigned int".