logReadCloser: ensure reader errors yield EOF
logReadCloser: ensure reader errors yield EOF

This change makes the underlying reader set their corresponding `eof` slot to true on termination.
This make the overall logReadCloser converge to EOF in case of errors of the underlying readers, therefore prevent spinning on read.

`bufio.Reader.ReadBytes` may not return io.EOF when `Close()` closes the underlying reader.
For instance, closing logReadCloser from the Scope App makes `bufio.Reader.ReadBytes` produce the following error: `http2: response body closed`.

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