Bug 5499: Remove support for src_as and dst_as ACLs (#2113)

Bug 5499: Remove support for src_as and dst_as ACLs (#2113)

Squid ACL initialization code calls asnCacheStart() and tries to connect
to an ASN server. If the configuration requires a cache_peer, that
connection fails because none of cache_peers are available an that time:

    WARNING: AS ... whois request failed

Since ASN-based ACLs are essentially unused and properly fixing this
bug requires significant effort work, we drop Autonomous System Numbers
instead. Any rare use cases may implement an external ACL helper with
similar functionality and more features.

Also removed no longer necessary radix.{c,h} code, "asndb" cache manager
report, and "asn" initiator value in transaction_initiator ACLs.