lib/osdep: Silence PVS-Studio

This line includes a check that exists above (off < 0); however, I
want the check to also exist here. It keeps the invariant
known at the point of use.

Signed-off-by: Joseph Benden <joe@benden.us>

lib/osdep/file.c

@@ -230,7 +230,7 @@ static int file_read(struct wif * wi,
 		ts->tv_nsec = pkh.tv_usec * 1000UL;
 	}
 
-	if (off < 0 || off >= len) return -1;
+	if (off < 0 || off >= len) return -1; //-V560
 	memcpy(h80211, &buf[off], rc);
 
 	return rc;