MDEV-11720 main.signal_demo3 fails in buildbot on labrador

increase stack size for labrador

include/my_pthread.h

@@ -673,7 +673,7 @@ extern void my_mutex_end(void);
   We need to have at least 256K stack to handle calls to myisamchk_init()
   with the current number of keys and key parts.
 */
-#define DEFAULT_THREAD_STACK	(291*1024L)
+#define DEFAULT_THREAD_STACK	(292*1024L)
 #endif
 
 #define MY_PTHREAD_LOCK_READ 0

mysql-test/r/mysqld--help.result

@@ -1496,7 +1496,7 @@ thread-pool-oversubscribe 3
 thread-pool-prio-kickup-timer 1000
 thread-pool-priority auto
 thread-pool-stall-limit 500
-thread-stack 297984
+thread-stack 299008
 time-format %H:%i:%s
 timed-mutexes FALSE
 tmp-table-size 16777216

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -3987,9 +3987,9 @@ READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	THREAD_STACK
 SESSION_VALUE	NULL
-GLOBAL_VALUE	297984
+GLOBAL_VALUE	299008
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	297984
+DEFAULT_VALUE	299008
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BIGINT UNSIGNED
 VARIABLE_COMMENT	The stack size for each thread

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -4869,9 +4869,9 @@ READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	THREAD_STACK
 SESSION_VALUE	NULL
-GLOBAL_VALUE	297984
+GLOBAL_VALUE	299008
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	297984
+DEFAULT_VALUE	299008
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BIGINT UNSIGNED
 VARIABLE_COMMENT	The stack size for each thread

mysql-test/suite/sys_vars/r/thread_stack_basic.result

 select @@global.thread_stack;
 @@global.thread_stack
-297984
+299008
 select @@session.thread_stack;
 ERROR HY000: Variable 'thread_stack' is a GLOBAL variable
 show global variables like 'thread_stack';
 Variable_name	Value
-thread_stack	297984
+thread_stack	299008
 show session variables like 'thread_stack';
 Variable_name	Value
-thread_stack	297984
+thread_stack	299008
 select * from information_schema.global_variables where variable_name='thread_stack';
 VARIABLE_NAME	VARIABLE_VALUE
-THREAD_STACK	297984
+THREAD_STACK	299008
 select * from information_schema.session_variables where variable_name='thread_stack';
 VARIABLE_NAME	VARIABLE_VALUE
-THREAD_STACK	297984
+THREAD_STACK	299008
 set global thread_stack=1;
 ERROR HY000: Variable 'thread_stack' is a read only variable
 set session thread_stack=1;