glibcLocales: disable parallelism to restore deterministic locales

The way `nixpkgs` runs parallel `localedef` instances shares
`--prefix=/build` flag. As a result `localedef` processes
non-deterministically extend the file with new locales (hopefully
without data corruption):

    https://github.com/NixOS/nixpkgs/issues/245360

Co-authored-by: Adam Joseph <54836058+amjoseph-nixpkgs@users.noreply.github.com>

pkgs/development/libraries/glibc/locales.nix

@@ -60,7 +60,11 @@
       echo SUPPORTED-LOCALES='${toString locales}' > ../glibc-2*/localedata/SUPPORTED
     '';
 
-  enableParallelBuilding = true;
+  # Current `nixpkgs` way of building locales is not compatible with
+  # parallel install. `locale-archive` is updated in parallel with
+  # multiple `localedef` processes and causes non-deterministic result:
+  #   https://github.com/NixOS/nixpkgs/issues/245360
+  enableParallelBuilding = false;
 
   makeFlags = (previousAttrs.makeFlags or []) ++ [
     "localedata/install-locales"