treewide: remove redundant rec

pkgs/development/libraries/science/benchmark/papi/default.nix

@@ -2,7 +2,7 @@
 , fetchurl
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   version = "5.6.0";
   pname = "papi";
 

pkgs/development/libraries/science/math/caffe2/default.nix

@@ -38,7 +38,7 @@ let
   '';
 
   cub = {
-    src = fetchFromGitHub rec {
+    src = fetchFromGitHub {
       owner  = "NVlabs";
       repo   = "cub";
       rev    = "v1.7.4";

pkgs/development/libraries/science/math/cudnn/generic.nix

@@ -10,7 +10,7 @@
 , addOpenGLRunpath
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   name = "cudatoolkit-${cudatoolkit.majorVersion}-cudnn-${version}";
 
   inherit version;

pkgs/development/libraries/science/math/liblapack/default.nix

@@ -11,7 +11,7 @@ let
   version = "3.8.0";
 in
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   pname = "liblapack";
   inherit version;
   src = fetchurl {