Revert "tests.cc-wrapper: filter unavailable gcc"

This reverts commit d33a309.

commit caused ofborg-eval to fail with

```
$ nix-build pkgs/top-level/release.nix -A tests.cc-wrapper.gcc10Stdenv.aarch64-darwin
       error: evaluation aborted with the following error message: 'cannot find attribute `tests.cc-wrapper.gcc10Stdenv''
```

on the 3 other platfomrs the attr is there

pkgs/test/default.nix

@@ -27,11 +27,7 @@ with pkgs;
         (stdenv.buildPlatform.isLinux && stdenv.buildPlatform.isx86_64) &&
         (stdenv.hostPlatform.isLinux && stdenv.hostPlatform.isx86_64)
       )) [
-        # Is a throw
         (filter (n: !lib.hasSuffix "MultiStdenv" n))
-      ] ++ [
-        # Has to be after the previous filter
-        (filter (n: lib.meta.availableOn stdenv.hostPlatform pkgs.${n}.cc ))
       ]);
     in lib.genAttrs pkgSets (name: callPackage ./cc-wrapper { stdenv = pkgs.${name}; });
   in recurseIntoAttrs {