[REVIEW-3-6 3-6-0] fix for fdo#52393, calc does not import manual row heights

[Markus Mohrhard]

Hey,

[1] fixes the problem that calc does not import manual row heights in
3-6. We need to mark the rows as manual row height in the row flags to
prevent overriding them with automatic row height calculation. You
won't see this problem in master because we are not updating the row
heights there at the moment.

IMHO this is a fix for 3-6-0 because it is a quite serious issue.

Regards,
Markus

[1] http://cgit.freedesktop.org/libreoffice/core/commit/?id=c55cfd273cf1d4666b91fc9a00c71b049c34adec