as-list: Grow faster to avoid too many re-allocations

as-list: Grow faster to avoid too many re-allocations

When we add a large number of ASes to the list, we will constantly
re-allocate the whole list because we are only growing it by 64 entries
at a time.

This patch changes that we will double the list in size every time we
run out of space and we will start with 1024 elements.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>