Merge with MySQL 5.1.53

Open issues:
- A better fix for #57688; Igor is working on this
- Test failure in index_merge_innodb.test ; Igor promised to look at this
- Some Innodb tests fails (need to merge with latest xtradb) ; Kristian promised to look at this.
 - Failing tests: innodb_plugin.innodb_bug56143 innodb_plugin.innodb_bug56632 innodb_plugin.innodb_bug56680 innodb_plugin.innodb_bug57255 
- Werror is disabled;  Should be enabled after merge with xtradb.

client/mysql.cc

@@ -3741,7 +3741,8 @@ print_tab_data(MYSQL_RES *result)
 }
 
 static int
-com_tee(String *buffer, char *line __attribute__((unused)))
+com_tee(String *buffer __attribute__((unused)),
+        char *line __attribute__((unused)))
 {
   char file_name[FN_REFLEN], *end, *param;
 
@@ -3800,7 +3801,8 @@ com_notee(String *buffer __attribute__((unused)),
 
 #ifdef USE_POPEN
 static int
-com_pager(String *buffer, char *line __attribute__((unused)))
+com_pager(String *buffer __attribute__((unused)),
+          char *line __attribute__((unused)))
 {
   char pager_name[FN_REFLEN], *end, *param;
 
@@ -3932,7 +3934,8 @@ com_rehash(String *buffer __attribute__((unused)),
 
 #ifdef USE_POPEN
 static int
-com_shell(String *buffer, char *line __attribute__((unused)))
+com_shell(String *buffer __attribute__((unused)),
+          char *line __attribute__((unused)))
 {
   char *shell_cmd;
 
@@ -4024,7 +4027,8 @@ com_connect(String *buffer, char *line)
 }
 
 
-static int com_source(String *buffer, char *line)
+static int com_source(String *buffer __attribute__((unused)),
+                      char *line)
 {
   char source_name[FN_REFLEN], *end, *param;
   LINE_BUFFER *line_buff;
@@ -4955,7 +4959,8 @@ static void init_username()
   }
 }
 
-static int com_prompt(String *buffer, char *line)
+static int com_prompt(String *buffer __attribute__((unused)),
+                      char *line)
 {
   char *ptr=strchr(line, ' ');
   prompt_counter = 0;