INT 21 P - Phar Lap 386/DOS-Extender - MODIFY MS-DOS MEMORY BLOCK               
	AX = 25C2h
	BX = new requested block size in paragraphs
	CX = real-mode paragraph address of memory block to modify
Return: CF clear if successful
	    EAX destroyed
	CF set on error
	    AX = error code
		07h MS-DOS memory control blocks destroyed
		08h insufficient memory
		09h invalid memory block address in CX
	    BX = size in paragraphs of largest available memory block
SeeAlso: AX=25C0h,AX=25C1h