Bug #58414 mysql_upgrade fails on dump upgrade between 5.1.53 -> 5.5.8

The problem was that mysql_upgrade failed because DROP DATABASE
refused to drop the 'performance_schema' database when the 
mysql.proc table definition was made temporarily invalid
by dump import.

This patch fixes the problem by adding the error resulting
from opening a damaged mysq.proc table (ER_CANNOT_LOAD_FROM_TABLE),
to the list of errors DROP DATABASE will ignore when trying
to lock stored procedures and functions before deletion.

This problem was a regression introduced by the patch for
Bug#57663.

Test case added to sp-destruct.test.

mysql-test/r/sp-destruct.result

@@ -150,3 +150,21 @@ Warnings:
 Error	1547	Column count of mysql.proc is wrong. Expected 20, found 19. The table is probably corrupted
 # Restore mysql.proc.
 drop table mysql.proc;
+#
+# Bug#58414 mysql_upgrade fails on dump upgrade between 5.1.53 -> 5.5.8
+#
+DROP TABLE IF EXISTS proc_backup;
+DROP DATABASE IF EXISTS db1;
+# Backup the proc table
+RENAME TABLE mysql.proc TO proc_backup;
+CREATE TABLE mysql.proc LIKE proc_backup;
+CREATE DATABASE db1;
+CREATE PROCEDURE db1.p1() SET @foo = 10;
+# Modify a field of the table.
+ALTER TABLE mysql.proc MODIFY comment CHAR (32);
+DROP DATABASE db1;
+Warnings:
+Error	1548	Cannot load from mysql.proc. The table is probably corrupted
+# Restore mysql.proc
+DROP TABLE mysql.proc;
+RENAME TABLE proc_backup TO mysql.proc;

mysql-test/t/sp-destruct.test

@@ -252,3 +252,30 @@ drop table mysql.proc;
 --remove_file $MYSQLTEST_VARDIR/tmp/proc.frm
 --remove_file $MYSQLTEST_VARDIR/tmp/proc.MYD
 --remove_file $MYSQLTEST_VARDIR/tmp/proc.MYI
+
+
+--echo #
+--echo # Bug#58414 mysql_upgrade fails on dump upgrade between 5.1.53 -> 5.5.8
+--echo #
+
+--disable_warnings
+DROP TABLE IF EXISTS proc_backup;
+DROP DATABASE IF EXISTS db1;
+--enable_warnings
+
+--echo # Backup the proc table
+RENAME TABLE mysql.proc TO proc_backup;
+CREATE TABLE mysql.proc LIKE proc_backup;
+
+CREATE DATABASE db1;
+CREATE PROCEDURE db1.p1() SET @foo = 10;
+
+--echo # Modify a field of the table.
+ALTER TABLE mysql.proc MODIFY comment CHAR (32);
+
+# This should not fail even if mysql.proc is invalid.
+DROP DATABASE db1;
+
+--echo # Restore mysql.proc
+DROP TABLE mysql.proc;
+RENAME TABLE proc_backup TO mysql.proc;

sql/sp.cc

@@ -1372,6 +1372,8 @@ public:
                         MYSQL_ERROR ** cond_hdl)
   {
     if (sql_errno == ER_NO_SUCH_TABLE ||
+        sql_errno == ER_CANNOT_LOAD_FROM_TABLE ||
+        sql_errno == ER_COL_COUNT_DOESNT_MATCH_PLEASE_UPDATE ||
         sql_errno == ER_COL_COUNT_DOESNT_MATCH_CORRUPTED)
       return true;
     return false;