treewide: use scons setup hook

Lots of packages can use it. Here is the list:

- jackmix
- klick
- mixx
- nova-filters
- rhvoice
- giv
- mypaint
- swift-im
- bombono
- mapnik
- serf
- nuitka
- pyexiv2
- godot
- hammer
- toluapp
- btanks
- dxx-rebirth
- endless-sky
- globulation
- the-powder-toy
- fceux
- gpsd
- mongodb
- rippled
- mariadb
- lprof

pkgs/servers/rippled/default.nix

@@ -15,12 +15,10 @@ stdenv.mkDerivation rec {
     sed -i -e "s@ENV = dict.*@ENV = os.environ@g" SConstruct
   '';
 
-  nativeBuildInputs = [ pkgconfig ];
-  buildInputs = [ scons openssl protobuf boost zlib ];
+  nativeBuildInputs = [ pkgconfig scons ];
+  buildInputs = [ openssl protobuf boost zlib ];
 
-  buildPhase = "scons";
-
-  installPhase = ''
+  postInstall = ''
     mkdir -p $out/bin
     cp build/rippled $out/bin/
   '';