Update trim_data to deal with locale fallback failure for unit

source/data/translit/root_subset.txt

Index: source/data/translit/root_subset.txt
diff --git a/source/data/translit/root_subset.txt b/source/data/translit/root_subset.txt
index 9dd51ab78db14261b30f5aa2544d5f8850a2e0e2..2f5c4baec34c5e9ce45016c421d6f781fa5c42c1 100644
--- a/source/data/translit/root_subset.txt
+++ b/source/data/translit/root_subset.txt
@@ -7,5 +7,10 @@
 // releases.
 //
 // Currently no rule sets in use.
+// Note that RuleBasedTransliteratorIDs block has to be present. Otherwise,
+// built-in transforms such as NFD/NFC would fail.
 
-root { }
+root {
+    RuleBasedTransliteratorIDs {
+    }
+}