freebsd.boot-install: wrap coreutils install instead of netbsd

netbsd can no longer compile under FreeBSD native early bootstrap
stdenv, so switch to coreutils. This only involves discarding the -l
flag. The -l flag causes a symlink instead of a copy to be installed, so
it is safe to discard during bootstrap.

pkgs/os-specific/bsd/freebsd/pkgs/boot-install.nix

@@ -1,10 +1,23 @@
 { buildPackages, freebsd-lib }:
 
-# Wrap NetBSD's install
+# Wrap GNU coreutils' install
+# The -l flag causes a symlink instead of a copy to be installed, so
+# it is safe to discard during bootstrap since coreutils does not support it.
+
 buildPackages.writeShellScriptBin "boot-install" (
   freebsd-lib.install-wrapper
   + ''
+    fixed_args=()
+    while [[ ''${#args[0]} > 0 ]]; do
+      case "''${args[0]}" in
+        -l)
+          args=("''${args[@]:2}")
+          continue
+      esac
+      fixed_args+=("''${args[0]}")
+      args=("''${args[@]:1}")
+    done
 
-    ${buildPackages.netbsd.install}/bin/xinstall "''${args[@]}"
+    ${buildPackages.coreutils}/bin/install "''${fixed_args[@]}"
   ''
 )