0.9.1.20:

	Fix typo in LOGAND-DERIVE-UNSIGNED-HIGH-BOUND (thanks to jsnell
	  for testing and rtoy for his CMUCL work on the same).

	(Since CMUCL has essentially the same code, a future commit
	 will add similar derivers for LOGXOR.  A more idiomatic CL
	 style will also be adopted.)