[CM] Possible bug in call-with-exit

[bil at ccrma.Stanford.EDU]

I think s7_call_with_catch needs to set a jump point for the
sc->longjmp_ok case, but I haven't figured out yet how to
capture the error handler result in all cases.
Here's what I have now:

(ca line 51216)

   else
     {
       declare_jump_info();
       TRACK(sc);
       store_jump_info(sc);
       set_jump_info(sc, S7_CALL_SET_JUMP); /* ?? */
       catch_cstack(p) = &new_goto_start;

       if (jump_loc == NO_JUMP)
	{
	  push_stack(sc, OP_CATCH, error_handler, p);
	  result = s7_call(sc, body, sc->nil);
	  if (((opcode_t)sc->stack_end[-1]) == OP_CATCH) sc->stack_end -= 4;
	}
       else result = sc->nil; /* wrong: should be the error handler 
result I think */

       restore_jump_info(sc);
     }

ffitest.c has test cases that break this code.

I'll poke at it tomorrow -- thanks for the bug report!