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.

doc/stdenv.xml

@@ -2433,30 +2433,6 @@ addEnvHooks "$hostOffset" myBashFunction
       </para>
      </listitem>
     </varlistentry>
-    <varlistentry>
-     <term>
-      paxctl
-     </term>
-     <listitem>
-      <para>
-       Defines the <varname>paxmark</varname> helper for setting per-executable
-       PaX flags on Linux (where it is available by default; on all other
-       platforms, <varname>paxmark</varname> is a no-op). For example, to
-       disable secure memory protections on the executable
-       <replaceable>foo</replaceable>
-<programlisting>
-      postFixup = ''
-        paxmark m $out/bin/<replaceable>foo</replaceable>
-      '';
-    </programlisting>
-       The <literal>m</literal> flag is the most common flag and is typically
-       required for applications that employ JIT compilation or otherwise need
-       to execute code generated at run-time. Disabling PaX protections should
-       be considered a last resort: if possible, problematic features should be
-       disabled or patched to work with PaX.
-      </para>
-     </listitem>
-    </varlistentry>
     <varlistentry>
      <term>
       autoPatchelfHook