neuron-mpi: remove appendToName to have a consistent package name for repology

pkgs/applications/science/biology/neuron/default.nix

···
 }:
 
 stdenv.mkDerivation rec {
-  pname = "neuron";
+  pname = "neuron${lib.optionalString useMpi "-mpi"}";
   version = "7.5";
 
   nativeBuildInputs = [ which pkg-config automake autoconf libtool ];

pkgs/top-level/all-packages.nix

···
 
   n3 = callPackage ../applications/science/biology/N3 { };
 
-  neuron = callPackage ../applications/science/biology/neuron {
-    python = null;
-  };
+  neuron = callPackage ../applications/science/biology/neuron { python = null; };
 
-  neuron-mpi = appendToName "mpi" (neuron.override {
-    useMpi = true;
-  });
+  neuron-mpi = neuron.override {useMpi = true; };
 
   neuron-full = neuron-mpi.override { python = python2; };