INT 21 P - Phar Lap 386/DOS-Extender - SET INT TO ALWAYS GAIN CNTRL IN PR. MODE 
	AX = 2506h
	CL = interrupt number
	DS:EDX = CS:EIP of protected-mode interrupt handler
Return: CF clear
Notes:	this function modifies both the real-mode low-memory interrupt
	  vector table and the protected-mode Interrupt Descriptor TableThe protected-mode table of descriptors specifying the handlers for up to 256 interrupts, and how to transfer control to each one.  See also Interrupt Vector Table. (IDTsee Interrupt Descriptor Table)
	interrupts occurring in real mode are resignaled in protected mode
	this function is also supported by FlashTek X-32VM