Define vApplicationGetTimerTaskMemory only when configUSE_TIMERS is set (#1104)

Otherwise it is very reasonable that config_TIMER_TASK_STACK_DEPTH is
undefined.
diff --git a/tasks.c b/tasks.c
index 7a65e7b..b5ab5ad 100644
--- a/tasks.c
+++ b/tasks.c
@@ -8617,7 +8617,7 @@
 #endif /* #if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configKERNEL_PROVIDED_STATIC_MEMORY == 1 ) && ( portUSING_MPU_WRAPPERS == 0 ) ) */
 /*-----------------------------------------------------------*/
 
-#if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configKERNEL_PROVIDED_STATIC_MEMORY == 1 ) && ( portUSING_MPU_WRAPPERS == 0 ) )
+#if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configKERNEL_PROVIDED_STATIC_MEMORY == 1 ) && ( portUSING_MPU_WRAPPERS == 0 ) && ( configUSE_TIMERS == 1 ) )
 
 /*
  * This is the kernel provided implementation of vApplicationGetTimerTaskMemory()
@@ -8638,7 +8638,7 @@
         *puxTimerTaskStackSize = configTIMER_TASK_STACK_DEPTH;
     }
 
-#endif /* #if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configKERNEL_PROVIDED_STATIC_MEMORY == 1 ) && ( portUSING_MPU_WRAPPERS == 0 ) ) */
+#endif /* #if ( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configKERNEL_PROVIDED_STATIC_MEMORY == 1 ) && ( portUSING_MPU_WRAPPERS == 0 ) && ( configUSE_TIMERS == 1 ) ) */
 /*-----------------------------------------------------------*/
 
 /*