[Fuego] LTP: fix the spreadsheet parser script

[Daniel Sangorrin]

Hi Tim,

I noticed that the rtonly spec was failing because it just produces
an rt.log but no spreadsheet. The following patches fix that.

[PATCH 1/2] LTP:ltp_process: dont crash if no sheets are generated
[PATCH 2/2] LTP:ltp_process: parse the rt.log into a new sheet

I am planning to focus on improving LTP soon, please let me know if
you are going to work on it as well to avoid collisions. Also if you
have any ideas about what you want to have changed in LTP let me know.

Best regards,
Daniel