qapi: Drop qapi_event_send_FOO()'s Error ** argument

The generated qapi_event_send_FOO() take an Error ** argument.  They
can't actually fail, because all they do with the argument is passing it
to functions that can't fail: the QObject output visitor, and the
@qmp_emit callback, which is either monitor_qapi_event_queue() or
event_test_emit().

Drop the argument, and pass &error_abort to the QObject output visitor
and @qmp_emit instead.

Suggested-by: Eric Blake <eblake@redhat.com>
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180815133747.25032-4-peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message rewritten, update to qapi-code-gen.txt corrected]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/blockjob.c b/blockjob.c
index be5903a..bf7ef48 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -315,8 +315,7 @@
                                         job->job.id,
                                         job->job.progress_total,
                                         job->job.progress_current,
-                                        job->speed,
-                                        &error_abort);
+                                        job->speed);
 }
 
 static void block_job_event_completed(Notifier *n, void *opaque)
@@ -338,8 +337,7 @@
                                         job->job.progress_current,
                                         job->speed,
                                         !!msg,
-                                        msg,
-                                        &error_abort);
+                                        msg);
 }
 
 static void block_job_event_pending(Notifier *n, void *opaque)
@@ -351,8 +349,7 @@
     }
 
     qapi_event_send_block_job_pending(job_type(&job->job),
-                                      job->job.id,
-                                      &error_abort);
+                                      job->job.id);
 }
 
 static void block_job_event_ready(Notifier *n, void *opaque)
@@ -367,7 +364,7 @@
                                     job->job.id,
                                     job->job.progress_total,
                                     job->job.progress_current,
-                                    job->speed, &error_abort);
+                                    job->speed);
 }
 
 
@@ -494,7 +491,7 @@
         qapi_event_send_block_job_error(job->job.id,
                                         is_read ? IO_OPERATION_TYPE_READ :
                                         IO_OPERATION_TYPE_WRITE,
-                                        action, &error_abort);
+                                        action);
     }
     if (action == BLOCK_ERROR_ACTION_STOP) {
         job_pause(&job->job);