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

data/fonts/fonts.xml

@@ -350,7 +350,7 @@
     <family lang="und-Zsye">
         <font weight="400" style="normal">NotoColorEmoji.ttf</font>
     </family>
-    <family>
+    <family lang="und-Zsym">
         <font weight="400" style="normal">NotoSansSymbols-Regular-Subsetted2.ttf</font>
     </family>
     <family>

tools/fonts/fontchain_lint.py

@@ -314,8 +314,11 @@ def check_emoji_defaults(default_emoji):
             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