Fix ambiguity in API if no matching system language is found

include/ports/SkTypeface_android.h

Index: include/ports/SkTypeface_android.h
diff --git a/include/ports/SkTypeface_android.h b/include/ports/SkTypeface_android.h
index 2166e08394a66cd11aa3210e0e93e5902f5a9b45..0996740031dc5f2e57f1c6ee8416261e430e6ac1 100644
--- a/include/ports/SkTypeface_android.h
+++ b/include/ports/SkTypeface_android.h
@@ -36,7 +36,9 @@ SK_API bool SkGetFallbackFamilyNameForChar(SkUnichar uni, SkString* name);
  *
  *  @param uni  The unicode character to use for the lookup.
  *  @param lang The null terminated string representing the BCP 47 language
- *              identifier for the preferred language
+ *              identifier for the preferred language. If there is no unique
+ *              fallback chain for that language the system's default language
+ *              will be used.
  *  @param name The family name of the font file containing the unicode character
  *              in the preferred language
  *  @return     true if a font is found and false otherwise