Remove duplicate extern declarations after r264573.
Makes things compile better.

Someone submit to:	OpenBSD
MFC after:		13 days
X-MFC with:		r264573
Stop casting the const char * to void * to char * to make compile more happy
after r264573.

Someone submit to:	OpenBSD
MFC after:	13 days
X-MFC with:	r264573
Correct AMD chipsets identification.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after:	2 weeks