We used to have a single boolean, "FascistFirewall".  Ages ago, in
tickets #17840 and #9067, we added an improved "ReachableAddresses"
mechanism.  It's time to rename related identifiers in the code for
consistency.  This closes #18106.

This is an automated commit, generated by this command:

./scripts/maint/rename_c_identifier.py \
        fascist_firewall_allows_address reachable_addr_allows \
        fascist_firewall_use_ipv6 reachable_addr_use_ipv6 \
        fascist_firewall_prefer_ipv6_impl reachable_addr_prefer_ipv6_impl \
        fascist_firewall_prefer_ipv6_orport reachable_addr_prefer_ipv6_orport \
        fascist_firewall_prefer_ipv6_dirport reachable_addr_prefer_ipv6_dirport \
        fascist_firewall_allows_address_addr reachable_addr_allows_addr \
        fascist_firewall_allows_address_ap reachable_addr_allows_ap \
        fascist_firewall_allows_base reachable_addr_allows_base \
        fascist_firewall_allows_ri_impl reachable_addr_allows_ri_impl \
        fascist_firewall_allows_rs_impl reachable_addr_allows_rs_impl \
        fascist_firewall_allows_rs reachable_addr_allows_rs \
        fascist_firewall_allows_md_impl reachable_addr_allows_md_impl \
        fascist_firewall_allows_node reachable_addr_allows_node \
        fascist_firewall_allows_dir_server reachable_addr_allows_dir_server \
        fascist_firewall_choose_address_impl reachable_addr_choose_impl \
        fascist_firewall_choose_address reachable_addr_choose \
        fascist_firewall_choose_address_base reachable_addr_choose_base \
        fascist_firewall_choose_address_rs reachable_addr_choose_from_rs \
        fascist_firewall_choose_address_ls reachable_addr_choose_from_ls \
        fascist_firewall_choose_address_node reachable_addr_choose_from_node \
        fascist_firewall_choose_address_dir_server reachable_addr_choose_from_dir_server