[media] drivers/media/pci: use memmove for overlapping regions

Change several memcpy() to memmove() in cases when the regions are
definitely overlapping; memcpy() of overlapping regions is undefined
behavior in C and can produce different results depending on the compiler,
the memcpy implementation, etc.

Cc: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/pci/cx18/cx18-vbi.c b/drivers/media/pci/cx18/cx18-vbi.c
index 6d3121f..add9964 100644
--- a/drivers/media/pci/cx18/cx18-vbi.c
+++ b/drivers/media/pci/cx18/cx18-vbi.c
@@ -84,7 +84,7 @@
 		   (the max size of the VBI data is 36 * 43 + 4 bytes).
 		   So in this case we use the magic number 'ITV0'. */
 		memcpy(dst + sd, "ITV0", 4);
-		memcpy(dst + sd + 4, dst + sd + 12, line * 43);
+		memmove(dst + sd + 4, dst + sd + 12, line * 43);
 		size = 4 + ((43 * line + 3) & ~3);
 	} else {
 		memcpy(dst + sd, "itv0", 4);