AROS: Update RTL structure TETask (execd)

Bring RTL (execd.inc) structure TETask up to date to unit exec (exec.pas).

This structure situated in the RTL was (literally) based on the MorphOS
version which is not compliant to AROS.

The original MorphOS TETask structure can still be 'activated' when the flag
AROS_MORPHOS_COMPATIBLE is defined when compiling the RTL and exec unit (as
is also the case in the original AROS repo).

rtl/aros/i386/execd.inc

@@ -694,6 +694,7 @@ const
 
 
 type
+{$ifdef AROS_MORPHOS_COMPATIBLE}
   PETask = ^TETask;
   TETask = record
     Message  : TMessage;
@@ -748,7 +749,29 @@ type
       * never assume a size of this structure
       * }
   end;
-
+{$else}
+  TETask = record
+    et_Message: TMessage;
+    et_Parent: PTask;       // Pointer to parent task
+    et_UniqueID: DWord;
+    et_Children: TMinList; // List of children
+    et_TrapAlloc: Word;
+    et_TrapAble: Word;
+    et_Result1: DWord;     // First result
+    et_Result2: Pointer;      // Result data pointer (AllocVec)
+    et_TaskMsgPort: TMsgPort;
+    et_Compatibility: array[0..3] of Pointer;   // Reserve this space for compiled software to access iet_startup and iet_acpd
+    et_MemPool: Pointer;              // Task's private memory pool
+{$ifdef aros}
+    et_Reserved: array[0..0] of PtrUInt; // MorphOS Private
+    et_TaskStorage: Pointer;          // Task Storage Slots
+{$else}
+    et_Reserved: array[0..1] of PtrUInt; // MorphOS Private
+{$endif}
+    et_RegFrame: Pointer;
+    // Internal fields follow
+  end;
+{$endif}
 
 type
   PTaskInitExtension = ^TTaskInitExtension;