treewide: remove paxutils from stdenv

More then one year ago we removed grsecurity kernels from nixpkgs:
https://github.com/NixOS/nixpkgs/pull/25277

This removes now also paxutils from stdenv.

pkgs/development/interpreters/python/cpython/3.7/default.nix

@@ -154,7 +154,6 @@ in stdenv.mkDerivation {
     touch $out/lib/python${majorVersion}/test/__init__.py
 
     ln -s "$out/include/python${majorVersion}m" "$out/include/python${majorVersion}"
-    paxmark E $out/bin/python${majorVersion}
 
     # Python on Nix is not manylinux1 compatible. https://github.com/NixOS/nixpkgs/issues/18484
     echo "manylinux1_compatible=False" >> $out/lib/${libPrefix}/_manylinux.py