safe including exception

alib2std/src/exception

+#ifndef __ALIB_INTERNAL_STD_EXTENSION_
+	#define __ALIB_INTERNAL_STD_EXTENSION_
+
+	#include "exception"
+
+	#undef __ALIB_INTERNAL_STD_EXTENSION_
+#else
+
+	#include <bits/../exception>
+
+#endif /* __ALIB_INTERNAL_STD_EXTENSION_ */