With --links/-l, a symlink is served as a .rclonelink object whose
content is the target path. A Range request with a start offset beyond
the target length (e.g. "Range: bytes=99999999999-") reached
openTranslatedLink and sliced the target string at that offset, panicking
with "slice bounds out of range".
Clamp the offset to the target length so an out-of-range start reads
empty, matching how a real file read past EOF behaves.