Fix bug in vdp_next_hint that was causing HINTs to fire repeatedly when they should not have fired at all based on an HINT interval that was larger than the number of active lines in the display

invalid_msg:
	.asciz "Invalid instruction at %X\n"

	.global m68k_invalid
m68k_invalid:
	lea invalid_msg(%rip), %rdi
	mov %ecx, %esi
	xor %rax, %rax
	call printf
	mov $1, %rdi
	call exit