libusb: Mark defualt smybol tag as latest stable version

As we might change the libusb ABI in 16, we should mark thje first
version as FBSD_1.8 instead of 1.9. Since versioning patch has not
landed for a long time, it makes sense to change it directly.

Discussed with: kib
Fixes: 527a82474c ("libusb: versioning symbols")
Sponsored by:   The FreeBSD Foundation

lib/libusb/Symbol.map

@@ -1,5 +1,5 @@
 
-FBSD_1.9 {
+FBSD_1.8 {
 	libusb_alloc_streams;
 	libusb_alloc_transfer;
 	libusb_attach_kernel_driver;