route.c: Whitespace cleanup.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
igmp.c: Whitespace cleanup.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
kern.c: Whitespace cleanup.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
mrt.[ch]: Cleanup.

Shorten and/or simplify local variable names for readability and
cleanup messy formatting.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>