Building system exit routines

There are no special considerations for building system exit routines. These routines can be linked with their callers or dynamically loaded and invoked. CEE.SCEESPC must be available at link-edit. If C library functions are required by the exit routines, the CEE.SCEELKED library must also be made available after CEE.SCEESPC. If the routines were compiled with OPT(2), the entry point must be explicitly named in the link-edit input.