[OpenBIOS] Allow building on Mac OS X

[BALATON Zoltan]

On Fri, 17 Apr 2015, Programmingkid wrote:
> What version of GCC did you use to add the usb support to OpenBIOS? My 
> gcc that causes the error message to show up is version 4.2.3.

4.8.2

Regards,
BALATON Zoltan