Remove libreoffice regression details - wheezy LTS

I attempted to reproduce this issue - which is presumably a regression
from fixing CVE-2017-3157 (it could also be CVE-2017-7870 which was also
fixed in the same release). I created a file with a chart in Libreoffice
sheet in Wheezy, and then upgraded to the security release version of
libreoffice. I couldn't reproduce the issue, charts worked perfectly.

I also attempted to look up other reports of the same issue and failed.
As a result, I suspect this regression was a once off, maybe related to
the specific file or the computer it was being run on.

It could also be related to the graphics card driver being used.

Not removing libreoffice entry, because there are two CVEs still
requiring attention.