[gtk-doc] mkdb: add role=example to detect those

[Stefan Sauer <stefkost src gnome org>]

commit b4ddc9af6a3040bdff91b5ed75ccfae16dd81b37
Author: Stefan Sauer <ensonic users sf net>
Date:   Sun Mar 18 19:32:14 2018 +0100

    mkdb: add role=example to detect those
    
    This simplifies matching example in mkhtml2.

 gtkdoc/mkdb.py |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/gtkdoc/mkdb.py b/gtkdoc/mkdb.py
index 62e790c..f5e8995 100644
--- a/gtkdoc/mkdb.py
+++ b/gtkdoc/mkdb.py
@@ -2689,8 +2689,9 @@ def ExpandAbbreviations(symbol, text):
 
     # Convert "|[" and "]|" into the start and end of program listing examples.
     # Support \[<!-- language="C" --> modifiers
-    text = re.sub(r'\|\[<!-- language="([^"]+)" -->', r'<informalexample><programlisting 
language="\1"><![CDATA[', text)
-    text = re.sub(r'\|\[', r'<informalexample><programlisting><![CDATA[', text)
+    text = re.sub(r'\|\[<!-- language="([^"]+)" -->',
+                  r'<informalexample><programlisting role="example" language="\1"><![CDATA[', text)
+    text = re.sub(r'\|\[', r'<informalexample><programlisting role="example"><![CDATA[', text)
     text = re.sub(r'\]\|', r']]></programlisting></informalexample>', text)
 
     # keep CDATA unmodified, preserve ulink tags (ideally we preseve all tags