Update to use the configuration / packaging scripts developed for dump1090-mutability.

Use a plain Conflicts: piaware on faup1090, as we don't actually want to replace it.
If regular piaware is installed, it'll provide a faup1090 binary anyway.
Include $(CPPFLAGS) when compiling faup1090, so it sees the hardening defines.
Remove default file that is now copied from a template in postinst.
Update changelog.