Revert "gcc: minimal hacky fixup for our pkgsi686Linux.nix"

This reverts commit b6ae8193ed.

pkgs/development/compilers/gcc/9/default.nix

@@ -245,12 +245,6 @@ stdenv.mkDerivation ({
 
   inherit (stdenv) is64bit;
 
-  # In this particular combination it stopped creating lib output at all.
-  # TODO: perhaps find a better fix?  (ideally understand what's going on)
-  postFixup = if crossStageStatic && targetPlatform.isMusl && targetPlatform.is32bit
-    then ''mkdir "$lib"''
-    else null;
-
   meta = {
     homepage = https://gcc.gnu.org/;
     license = stdenv.lib.licenses.gpl3Plus;  # runtime support libraries are typically LGPLv3+