{apptainer,singularity}: enable __structuredAttrs

pkgs/applications/virtualization/singularity/generic.nix

@@ -109,6 +109,7 @@ in
   # go is used to compile extensions when building container images
   allowGoReference = true;
 
+  __structuredAttrs = true;
   strictDeps = true;
 
   passthru = {
@@ -206,15 +207,10 @@ in
   '';
 
   postConfigure = ''
-    # Code borrowed from pkgs/stdenv/generic/setup.sh configurePhase()
-
     # set to empty if unset
     : ''${configureFlags=}
 
-    # shellcheck disable=SC2086
-    $configureScript -V ${version} "''${prefixKey:---prefix=}$prefix" $configureFlags "''${configureFlagsArray[@]}"
-
-    # End of the code from pkgs/stdenv/generic/setup.sh configurPhase()
+    $configureScript -V ${version} "''${prefixKey:---prefix=}$prefix" "''${configureFlags[@]}"
   '';
 
   buildPhase = ''