In mysql-5.0.x tables `general_log` and `slow_log` don't have to exist.
When we try to get dump of mysql database of mysql-5.0.x server using
client mysql-5.1.x or newer, which expect these tables to exist, mysqldump
will crash with the following error:

  mysqldump: Couldn't execute 'show create table `general_log`': Table
  'mysql.general_log' doesn't exist (1146)

This is reported at http://bugs.mysql.com/bug.php?id=65670

This patch adds checking if tables `general_log` and `slow_log` exist before
reading their structure.

diff -up mysql-5.1.66/client/mysqldump.c.logs mysql-5.1.66/client/mysqldump.c
--- mysql-5.1.66/client/mysqldump.c.logs	2012-09-07 16:14:06.000000000 +0200
+++ mysql-5.1.66/client/mysqldump.c	2012-11-28 15:33:00.116328380 +0100
@@ -4269,6 +4269,31 @@ my_bool include_table(const uchar *hash_
 }
 
 
+/* Return 1 if table exists in db */
+
+static my_bool get_table_exists(char *table, char *db)
+{
+  char query_buff[QUERY_LENGTH];
+  MYSQL_RES  *result;
+  MYSQL_ROW row;
+  my_bool return_value = 0;
+ 
+  DBUG_ENTER("get_table_exists");
+  my_snprintf(query_buff, sizeof(query_buff),
+              "SELECT COUNT(0) AS `Exists` "
+              "FROM `INFORMATION_SCHEMA`.`TABLES` WHERE "
+              "TABLE_SCHEMA = '%s' AND TABLE_NAME = '%s'",
+              db, table); 
+
+  mysql_query_with_error_report(mysql, &result, query_buff);
+  if (row= mysql_fetch_row(result))
+    return_value = (strcmp(row[0], "0") != 0);
+
+  mysql_free_result(result);
+  DBUG_RETURN(return_value);
+}
+
+
 static int dump_all_tables_in_db(char *database)
 {
   char *table;
@@ -4292,17 +4317,24 @@ static int dump_all_tables_in_db(char *d
     char table_type[NAME_LEN];
     char ignore_flag;
     uint num_fields;
-    num_fields= get_table_structure((char *) "general_log", 
-                                    database, table_type, &ignore_flag);
-    if (num_fields == 0)
-      verbose_msg("-- Warning: get_table_structure() failed with some internal "
-                  "error for 'general_log' table\n");
-    num_fields= get_table_structure((char *) "slow_log", 
-                                    database, table_type, &ignore_flag);
-    if (num_fields == 0)
-      verbose_msg("-- Warning: get_table_structure() failed with some internal "
-                  "error for 'slow_log' table\n");
+    if (get_table_exists((char *) "general_log", database))
+    {
+      num_fields= get_table_structure((char *) "general_log", 
+                                      database, table_type, &ignore_flag);
+      if (num_fields == 0)
+        verbose_msg("-- Warning: get_table_structure() failed with some internal "
+                    "error for 'general_log' table\n");
+    }
+    if (get_table_exists((char *) "slow_log", database))
+    {
+      num_fields= get_table_structure((char *) "slow_log", 
+                                      database, table_type, &ignore_flag);
+      if (num_fields == 0)
+        verbose_msg("-- Warning: get_table_structure() failed with some internal "
+                    "error for 'slow_log' table\n");
+    }
   }
+
   if (lock_tables)
   {
     DYNAMIC_STRING query;