INT 62 u - FGDRIVER v4.02 - "FG_TESTMODE" - CHECK IF VIDEO MODE AVAILABLE
	AX = 00C7h
	BX = desired video mode (00h-17h, also 18h-1Dh after "FG_SVGAINIT")
	CX = required number of video pages (ignore memory size if <= 0)
Return: AX = status
	    0000h mode not available with requested number of pages
	    0001h mode is available
Note:	the FGDRIVER functions are rearranged with each major release, but
	  their parameters do not change (see #03474 at AX=0000h)
SeeAlso: AX=0005h,AX=00B0h