A fix and test case for Bug#16164 "Easter egg":

SHOW AUTHORS caused 'Packets out of order' in stored functions:
add the corresponding SQLCOM to sp_get_flags_for_command so that
it'd return sp-related flags for it. 
Fix Bug#17403 "Events: packets out of order with show create event"
in the same chaneset.


mysql-test/r/events.result:
  Update the results (Bug#17403)
mysql-test/r/sp-error.result:
  Test results fixed (Bug#16164)
mysql-test/t/events.test:
  Add a test case for Bug#17403 "Events: packets out of order with
  show create event"
mysql-test/t/sp-error.test:
  Add a test case for Bug#16164 "Easter egg"
sql/sp_head.cc:
  Add SHOW AUTHORS to the list of commands that return a result
  set: such commands are not allowed in stored functions and
  triggers. Add SHOW CREATE EVENT for the same reason.

mysql-test/t/sp-error.test

@@ -1691,6 +1691,24 @@ drop function if exists bug16896;
 --error ER_SP_NO_AGGREGATE
 create aggregate function bug16896() returns int return 1;
 
+#
+# End of 5.0 tests
+#
+
+#
+# Bug#16164 "Easter egg": check that SHOW AUTHORS is disabled in
+# stored functions/triggers
+#
+--disable_warnings
+drop function if exists bug16164;
+--enable_warnings
+delimiter |;
+--error ER_SP_NO_RETSET
+create function bug16164() returns int
+begin
+  show authors;
+  return 42;
+end|
 
 #
 # BUG#NNNN: New bug synopsis