[gtk-doc] Add a comment explaining previous change.

[Stefan Sauer <stefkost src gnome org>]

commit e37b083ebe1516152808fe76968512b789cb2ec0
Author: Stefan Sauer <ensonic users sf net>
Date:   Fri Oct 19 20:22:09 2018 +0200

    Add a comment explaining previous change.

 gtkdoc/scangobj.py | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gtkdoc/scangobj.py b/gtkdoc/scangobj.py
index c28d6ba..0de791b 100644
--- a/gtkdoc/scangobj.py
+++ b/gtkdoc/scangobj.py
@@ -1203,13 +1203,16 @@ def execute_command(options, description, command):
         return 1
     return 0
 
+
 def split_with_quote(string):
+    # This is required to handle CFLAGS such as -DG_LOG_DOMAIN="tester"
     lex = shlex.shlex(string)
     lex.quotes = '"'
     lex.whitespace_split = True
     lex.commenters = ''
     return list(lex)
 
+
 def run(options):
     logging.info('options: %s', str(options.__dict__))