JCXZ/JECXZ - Jump if Register (E)CX is Zero

	Usage:	JCXZ	label
		JECXZ	label  (386+ only)
	Modifies flags: None


	Causes execution to branch to "label" if register CX is zero.  Uses
	unsigned comparision.

				 Clocks			Size
	Operands	 808x  286   386   486		Bytes

	label:	jump	  18   8+m   9+m    8		  2
		no jump	   6	4     5	    5


	- see Instruction Timing