create messages_fulltext table when creating db from scratch

k9mail/src/main/java/com/fsck/k9/mailstore/StoreSchemaDefinition.java

@@ -200,6 +200,8 @@ class StoreSchemaDefinition implements LockableDatabase.SchemaDefinition {
                 "BEGIN " +
                 "DELETE FROM message_parts WHERE root = OLD.message_part_id;" +
                 "END");
+
+        db.execSQL("CREATE VIRTUAL TABLE messages_fulltext USING fts4 (fulltext)");
     }