cudaPackages.cuda_nvcc: back-end cc already exposes the c++ stdlib

Unbreaks evaluation after the refactoring in
86c28ee
(NixOS#282220).

Explicitly extending nvcc's LIBRARIES may have been redundant (building
something mildly cursed like jaxlib may be necessary to verify)

Previously:
```
❯ NIXPKGS_ALLOW_UNFREE=1 nix-instantiate '.' -A tests.cuda
...
       error: necessary to fix CI
❯ nix build -f '.' --arg config '{ allowUnfree = true; }' -L python3Packages.torchWithCuda
...
       error: necessary to fix CI
```

Now:
```
❯ NIXPKGS_ALLOW_UNFREE=1 nix-instantiate '.' -A tests.cuda
/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-cuda-samples-12.2.drv
/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-saxpy-unstable-2023-07-11.drv
...
```

pkgs/development/cuda-modules/cuda/overrides.nix

@@ -112,7 +112,6 @@ attrsets.filterAttrs (attr: _: (builtins.hasAttr attr prev)) {
         useCcForLibs = true;
         gccForLibs = ccForLibs-wrapper.cc;
       };
-      cxxStdlibDir = ccForLibs-wrapper.cxxStdlib.solib or (throw "necessary to fix CI");
     in
     {
 
@@ -149,7 +148,6 @@ attrsets.filterAttrs (attr: _: (builtins.hasAttr attr prev)) {
 
           # Fix a compatible backend compiler
           PATH += ${lib.getBin cc}/bin:
-          LIBRARIES += "-L${cxxStdlibDir}/lib"
 
           # Expose the split-out nvvm
           LIBRARIES =+ -L''${!outputBin}/nvvm/lib