ntdll: Preserve the stack red zone on ARM64.

Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/ntdll/signal_arm64.c

@@ -476,6 +476,7 @@ static EXCEPTION_RECORD *setup_exception( ucontext_t *sigcontext, raise_func fun
     {
         CONTEXT           context;
         EXCEPTION_RECORD  rec;
+        void             *redzone[2];
     } *stack;
     DWORD exception_code = 0;