65682da [tests] bind functional test nodes to 127.0.0.1 (Sjors Provoost)
Pull request description:
Prevents OSX firewall allow-this-application-to-accept-inbound-connections permission popups and is generally safer.
To test, make an arbitrary whitespace change to `src/bitcoind.cpp` and recompile. This normally resets the firewall's memory.
Easiest way to reproduce a popup without running the test suite:
```sh
src/bitcoind -regtest -bind=127.0.0.1 # No popup
src/bitcoind -regtest # Popup
```
Tree-SHA512: ffa92f148a2ead2ceca978c285882979639be23eb31ad6a27aa81df9fdddba5d493719c92c09a351a81d638f6f739c351a721e42168d77ead60abe074df773d6