[glib] mkenums: Don't raise when unlinking a file that does not exist

[Philip Withnall <pwithnall src gnome org>]

commit 34148fc9b9edd8501ed2b0d483d0b8c942ac28ab
Author: Sam Spilsbury <sam endlessm com>
Date:   Fri Oct 27 21:42:46 2017 +0800

    mkenums: Don't raise when unlinking a file that does not exist
    
    Fixes https://bugzilla.gnome.org/show_bug.cgi?id=789637

 gobject/glib-mkenums.in |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/gobject/glib-mkenums.in b/gobject/glib-mkenums.in
index 2d6a8c8..e8124b8 100755
--- a/gobject/glib-mkenums.in
+++ b/gobject/glib-mkenums.in
@@ -708,5 +708,11 @@ write_output("\n" + comment + "\n")
 if tmpfile is not None:
     tmpfilename = tmpfile.name
     tmpfile.close()
-    os.unlink(options.output)
+
+    try:
+        os.unlink(options.output)
+    except OSError as error:
+        if error.errno != errno.ENOENT:
+            raise error
+
     os.rename(tmpfilename, options.output)