Fix incorrect emoji presentation for 'Zsym' script

If the language tag "und-Zsym" is applied to a TextView, the default
presentation should be text-style. However, it didn't work before this
patch, due to a lack of "und-Zsym" language tag in fonts.xml.

Bug: 31297127
Change-Id: Ieed8fe1532806dd1e75c58aa0d7a724bfeed7796
diff --git a/tools/fonts/fontchain_lint.py b/tools/fonts/fontchain_lint.py
index 372cb20..219fa2d 100755
--- a/tools/fonts/fontchain_lint.py
+++ b/tools/fonts/fontchain_lint.py
@@ -314,8 +314,11 @@
             continue
         # For later fonts, we only check them if they have a script
         # defined, since the defined script may get them to a higher
-        # score even if they appear after the emoji font.
-        if emoji_font_seen and not record.scripts:
+        # score even if they appear after the emoji font. However,
+        # we should skip checking the text symbols font, since
+        # symbol fonts should be able to override the emoji display
+        # style when 'Zsym' is explicitly specified by the user.
+        if emoji_font_seen and (not record.scripts or 'Zsym' in record.scripts):
             continue
 
         # Check default emoji-style characters