uutils-coreutils: symlink multicall aliases to fix closure size

Upstream commit fb76aba95b35 changed the default LN from `ln -sf` to
`ln -f`, so each utility alias is now a hardlink to the 14 MiB
multicall binary. NAR serialization does not preserve hardlinks, so
every alias is stored and downloaded as a full copy, taking the
closure from ~61 MiB to ~1.5 GiB.

https://github.com/uutils/coreutils/commit/fb76aba95b35bf12b0175d67e4b10b2f9910c5df

pkgs/by-name/uu/uutils-coreutils/package.nix

@@ -86,6 +86,10 @@ stdenv.mkDerivation (finalAttrs: {
 
   env = {
     CARGO_BUILD_TARGET = stdenv.hostPlatform.rust.rustcTargetSpec;
+    # Upstream uses hardlinks for the multicall aliases by default, but NAR
+    # serialization does not preserve hardlinks, exploding the closure to
+    # ~100 copies of the 14 MiB binary.
+    LN = "ln -sf";
   }
   // lib.optionalAttrs selinuxSupport {
     SELINUX_INCLUDE_DIR = "${lib.getInclude libselinux}/include";