stdenv/check-meta: Remove outputsToInstall list concat from common meta

Normally either of "bin" or "out" will hit first so we can avoid dynamic looping altogether.

pkgs/stdenv/generic/check-meta.nix

@@ -443,6 +443,7 @@ let
   commonMeta = { validity, attrs, pos ? null, references ? [ ] }:
     let
       outputs = attrs.outputs or [ "out" ];
+      hasOutput = out: builtins.elem out outputs;
     in
     {
       # `name` derivation attribute includes cross-compilation cruft,
@@ -461,10 +462,13 @@ let
       #   Services and users should specify outputs explicitly,
       #   unless they are comfortable with this default.
       outputsToInstall =
-        let
-          hasOutput = out: builtins.elem out outputs;
-        in
-        [ (findFirst hasOutput null ([ "bin" "out" ] ++ outputs)) ]
+        [
+          (
+            if hasOutput "bin" then "bin"
+            else if hasOutput "out" then "out"
+            else findFirst hasOutput null outputs
+          )
+        ]
         ++ optional (hasOutput "man") "man";
     }
     // attrs.meta or { }