qubes/ext/r3compat: update firewall handling for new API
qubes/ext/r3compat: update firewall handling for new API

QubesOS/qubes-issues#1815

QubesOS/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin