[REVIEW 3-6] fix for fdo#56958, two problems around the sort dialog

[Markus Mohrhard]

Hey,

[1] and [2] fix two problems around the sort dialog that have been
introduced with the unlimited number of sort entries. We have to make
sure that we don't access out of bounds entries.

Regards,
Markus

[1] http://cgit.freedesktop.org/libreoffice/core/commit/?id=cd545dcf511daedd548c11159b8c244f272e9cb6
[2] http://cgit.freedesktop.org/libreoffice/core/commit/?id=c45b6496e87fe74570a41821bc5f4fbdb3d3cf8e