Fix libusb related [-Werror=deprecated-declarations] warnings

See http://libusb.sourceforge.net/api-1.0/group__libusb__lib.html

sanei/sanei_usb.c

@@ -1404,7 +1404,12 @@ sanei_usb_init (void)
 	}
 #ifdef DBG_LEVEL
       if (DBG_LEVEL > 4)
+#if LIBUSB_API_VERSION >= 0x01000106
+        libusb_set_option (sanei_usb_ctx, LIBUSB_OPTION_LOG_LEVEL,
+                           LIBUSB_LOG_LEVEL_INFO);
+#else
 	libusb_set_debug (sanei_usb_ctx, 3);
+#endif /* LIBUSB_API_VERSION */
 #endif /* DBG_LEVEL */
     }
 #endif /* HAVE_LIBUSB */

tools/sane-find-scanner.c

@@ -2009,7 +2009,12 @@ main (int argc, char **argv)
 	  }
 
 	if (verbose > 3)
+#if LIBUSB_API_VERSION >= 0x01000106
+          libusb_set_option (sfs_usb_ctx, LIBUSB_OPTION_LOG_LEVEL,
+                             LIBUSB_LOG_LEVEL_INFO);
+#else
 	  libusb_set_debug (sfs_usb_ctx, 3);
+#endif
 
 	devcnt = libusb_get_device_list (sfs_usb_ctx, &devlist);
 	if (devcnt < 0)