[gtk-doc] fixxref: don't scan dirs that don't exist

[Stefan Sauer <stefkost src gnome org>]

commit 8af1966e2bcce3db2b0124e396e34946f7c0ec90
Author: Stefan Sauer <ensonic users sf net>
Date:   Sun Apr 23 17:35:49 2017 +0200

    fixxref: don't scan dirs that don't exist
    
    Fixes #781443

 gtkdoc/fixxref.py |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/gtkdoc/fixxref.py b/gtkdoc/fixxref.py
index 406a71e..4893b87 100755
--- a/gtkdoc/fixxref.py
+++ b/gtkdoc/fixxref.py
@@ -120,10 +120,12 @@ def ScanIndices(scan_dir, use_absolute_links):
 
     logging.info('Scanning index directory: %s, absolute: %d', scan_dir, use_absolute_links)
 
-    # This array holds any subdirectories found.
-    subdirs = []
-
     # TODO(ensonic): this code is the same as in rebase.py
+    if not os.path.isdir(scan_dir):
+        logging.info('Cannot open dir "%s"', scan_dir)
+        return
+
+    subdirs = []
     for entry in os.listdir(scan_dir):
         full_entry = os.path.join(scan_dir, entry)
         if os.path.isdir(full_entry):