New netem-related functionality:
Added ability to save new settings to the kernel. In netem.c, the
netem_get_opts() stub has been replaced with netem_build_msg() which
manipulates the nl_msg data directly and returns an error code instead
of a new nl_msg. Modifications to qdisc_build() in qdisc.c and struct
rtnl_qdisc_ops were necessary for this.
Added support for getting/setting corruption probability/correlation.
Added support for setting a delay distribution.
Fixed tbf_msg_parser() to call tbf_alloc() instead of tbf_qdisc() to
prevent a seg fault.
This interface was internal so far which required all code defining
caches to be compiled with the sources available.
In order to simplify the interface, the co_msg_parser prototype was
changed to take the struct nl_parser_param directly instead of a
void *. It used to be void * because the co_msg_parser was directly
passed as the NL_CB_VALID callback function.
