score: Delete _Thread_Dispatch_set_disable_level()

This function was only used in some tests and can be replaced with other
functions.

testsuites/rhealstone/rhilatency/ilatency.c

@@ -93,7 +93,6 @@ rtems_task Task_1(
 {
   Install_tm27_vector( Isr_handler ) ;
   Interrupt_nest = 0;
-  _Thread_Dispatch_set_disable_level( 0 );
 
   /* Benchmark code */
   benchmark_timer_initialize();

testsuites/tmtests/tm26/task1.c

@@ -584,7 +584,9 @@ void complete_test( void )
   set_thread_heir( _Thread_Get_executing() );
   set_thread_dispatch_necessary( false );
 
-  _Thread_Dispatch_set_disable_level( 0 );
+  for (index = 0; index < 2 * OPERATION_COUNT; ++index) {
+    _Thread_Unnest_dispatch();
+  }
 
   /*
    *  Now dump all the times

testsuites/tmtests/tm27/task1.c

@@ -112,8 +112,6 @@ rtems_task Task_1(
 
   Interrupt_nest = 0;
 
-  _Thread_Dispatch_set_disable_level( 0 );
-
   Interrupt_occurred = 0;
 
   benchmark_timer_initialize();
@@ -145,7 +143,7 @@ rtems_task Task_1(
    *  No preempt .. nested
    */
 
-  _Thread_Dispatch_set_disable_level( 1 );
+  _Thread_Disable_dispatch();
 
   Interrupt_nest = 1;
 
@@ -159,7 +157,7 @@ rtems_task Task_1(
 #endif
   Interrupt_return_time = benchmark_timer_read();
 
-  _Thread_Dispatch_set_disable_level( 0 );
+  _Thread_Unnest_dispatch();
 
   put_time(
     "rtems interrupt: entry overhead returns to nested interrupt",
@@ -181,8 +179,6 @@ rtems_task Task_1(
    *  Does a preempt .. not nested
    */
 
-  _Thread_Dispatch_set_disable_level( 0 );
-
 #if defined(RTEMS_SMP)
   _ISR_Disable_without_giant(level);
 #endif
@@ -253,8 +249,6 @@ rtems_task Task_2(
    *  Switch back to the other task to exit the test.
    */
 
-  _Thread_Dispatch_set_disable_level( 0 );
-
 #if defined(RTEMS_SMP)
   rtems_interrupt_disable(level);
 #endif