INT 21 - Q87, Q387 - INSTALLATION CHECK

	AX = 4321h
	BX = 0000h
	EAX = 87654321h (entire EAX value is required, not just AX)
Return: EAX = 12345678h if installed
Program: Q387 (renamed to Q87 as of v3.7) is a math coprocessor emulator from
	  Quickware
Note:	this function is available only in virtual-86 mode in older versions;
	  newer versions also provide it in MS Windows 16- and 32-bit protected
	  mode
SeeAlso: AX=4321h/BX=0001h,AX=4321h/BX=0002h,INT 67/AX=4321h