score: Add nest level to interal error state

Add Internal_errors_Information::nest_level.  This helps to detect
recursive calls to _Internal_error_Occurred().

cpukit/score/include/rtems/score/interr.h

@@ -88,6 +88,13 @@ typedef struct {
   bool                    is_internal;
   /** This is the error code. */
   Internal_errors_t       the_error;
+
+  /**
+   * @brief The internal error nest level.
+   *
+   * This helps to detect recursive calls to _Internal_error_Occurred().
+   */
+  uint32_t                nest_level;
 } Internal_errors_Information;
 
 /**

cpukit/score/src/interr.c

@@ -55,6 +55,8 @@ void _Internal_error_Occurred(
   _Internal_errors_What_happened.is_internal = is_internal;
   _Internal_errors_What_happened.the_error   = the_error;
 
+  ++_Internal_errors_What_happened.nest_level;
+
   _User_extensions_Fatal( the_source, is_internal, the_error );
 
   _System_state_Set( SYSTEM_STATE_FAILED );