elog-gen.py : implement error inheritance

If an error inherits another error (via the error YAML interface), have
the child error inherit parent's metadata. Only single inheritance is
supported as of now.

Change-Id: I9ff295f4db04a9c5389f66e04f5d28287f9628a9
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
diff --git a/tools/elog-gen.py b/tools/elog-gen.py
index a6fdb1f..e9f4fc0 100755
--- a/tools/elog-gen.py
+++ b/tools/elog-gen.py
@@ -151,7 +151,8 @@
     f.write(template.render(
             errors=errors, error_msg=error_msg,
             error_lvl=error_lvl, meta=meta,
-            meta_data=meta_data, error_namespace=i_error_namespace))
+            meta_data=meta_data, error_namespace=i_error_namespace,
+            parents=parents))
     f.close()