mkNugetSource: Remove meta.licenses attribute

- It's useless. The correct attribute name would be `license` and not
  `licenses`. Meaning setting this never did anything useful.
- It used IFD in its implementation, meaning to know what the licenses
  of a nuget source are, you first had to build that nuget source. This
  defeats the point of having license checks in the first place.
- IFD is not allowed by the nixpkgs CI and build farm anyway.

pkgs/build-support/dotnet/make-nuget-source/default.nix

@@ -5,34 +5,23 @@
 , deps ? []
 }:
 
-let
-  nuget-source = stdenvNoCC.mkDerivation {
-    inherit name;
+stdenvNoCC.mkDerivation {
+  inherit name;
 
-    nativeBuildInputs = [ python3 ];
+  nativeBuildInputs = [ python3 ];
 
-    buildCommand = ''
-      mkdir -p $out/{lib,share}
+  buildCommand = ''
+    mkdir -p $out/{lib,share}
 
-      # use -L to follow symbolic links. When `projectReferences` is used in
-      # buildDotnetModule, one of the deps will be a symlink farm.
-      find -L ${lib.concatStringsSep " " deps} -type f -name '*.nupkg' -exec \
-        ln -s '{}' -t $out/lib ';'
+    # use -L to follow symbolic links. When `projectReferences` is used in
+    # buildDotnetModule, one of the deps will be a symlink farm.
+    find -L ${lib.concatStringsSep " " deps} -type f -name '*.nupkg' -exec \
+      ln -s '{}' -t $out/lib ';'
 
-      # Generates a list of all licenses' spdx ids, if available.
-      # Note that this currently ignores any license provided in plain text (e.g. "LICENSE.txt")
-      python ${./extract-licenses-from-nupkgs.py} $out/lib > $out/share/licenses
-    '';
+    # Generates a list of all licenses' spdx ids, if available.
+    # Note that this currently ignores any license provided in plain text (e.g. "LICENSE.txt")
+    python ${./extract-licenses-from-nupkgs.py} $out/lib > $out/share/licenses
+  '';
 
-    meta.description = description;
-  } // { # We need data from `$out` for `meta`, so we have to use overrides as to not hit infinite recursion.
-    meta = nuget-source.meta // {
-      licenses = let
-        # TODO: avoid IFD
-        depLicenses = lib.splitString "\n" (builtins.readFile "${nuget-source}/share/licenses");
-      in lib.flatten (lib.forEach depLicenses (spdx:
-        lib.optionals (spdx != "") (lib.getLicenseFromSpdxId spdx)
-      ));
-    };
-  };
-in nuget-source
+  meta.description = description;
+}