Fix for bug#21416 SP: Recursion level higher than zero needed for non-recursive call

The following procedure was not possible if max_sp_recursion_depth is 0
create procedure show_proc() show create procedure show_proc;
  
Actually there is no recursive call but the limit is checked.
  
Solved by temporarily increasing the thread's limit just before the fetch from cache
and decreasing after that.


mysql-test/r/sp.result:
  update result
mysql-test/t/sp.test:
  Test for bug #21416 SP: Recursion level higher than zero needed for non-recursive call
sql/sp.cc:
  Increase the max_sp_recursion_depth temporarily for SHOW CREATE PROCEDURE call.
  This call is in fact not recursive but is counted as such. Outcome, it will work
  always but if max_sp_recursion_depth is reached we are going to cache one more
  sp_head instance.

mysql-test/r/sp.result

@@ -5387,4 +5387,11 @@ BEGIN
 RETURN 1;
 END|
 ERROR HY000: String '1234567890abcdefghij1234567890abcdefghij1234567890abcdefghijQWERTY' is too long for host name (should be no longer than 60)
+drop procedure if exists bug21416|
+create procedure bug21416() show create procedure bug21416|
+call bug21416()|
+Procedure	sql_mode	Create Procedure
+bug21416		CREATE DEFINER=`root`@`localhost` PROCEDURE `bug21416`()
+show create procedure bug21416
+drop procedure bug21416|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -6312,6 +6312,16 @@ BEGIN
 END|
 
 
+#
+# BUG#21416: SP: Recursion level higher than zero needed for non-recursive call
+#
+--disable_warnings
+drop procedure if exists bug21416|
+--enable_warnings
+create procedure bug21416() show create procedure bug21416|
+call bug21416()|
+drop procedure bug21416|
+
 #
 # BUG#NNNN: New bug synopsis
 #