lib/modules: Use strict fold' as recursiveUpdate is also strict

recursiveUpdate does not produce an attrset until it has evaluated
both its arguments to weak head normal form.

    nix-repl> lib.recursiveUpdate (throw "a") (throw "b")
    error: b

    nix-repl> lib.recursiveUpdate (throw "a") {}
    error: a

1 files changed, 1 insertions, 2 deletions

diff --git a/lib/modules.nix b/lib/modules.nix
index 99f51d22dcd..e3abf846625 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -13,7 +13,6 @@ let
     elem
     filter
     findFirst
-    foldl
     foldl'
     getAttrFromPath
     head
@@ -863,7 +862,7 @@ rec {
   mkMergedOptionModule = from: to: mergeFn:
     { config, options, ... }:
     {
-      options = foldl recursiveUpdate {} (map (path: setAttrByPath path (mkOption {
+      options = foldl' recursiveUpdate {} (map (path: setAttrByPath path (mkOption {
         visible = false;
         # To use the value in mergeFn without triggering errors
         default = "_mkMergedOptionModule";