Commit f991b842 (tdf#108524 sw: attempt
to split section frames inside table cells, 2017-06-19) added initial
support for multi-page sections inside a table cell, but turns out this
only worked in case at the split point there was a long enough
paragraph, so it was split into two (a "master" text frame and a
"follow" one), and then the follow was moved to the next page by
SwContentFrame::MakeAll(), with the MoveFwd() call in the "If a Follow
sits next to its Master and doesn't fit, we know it can be moved right
now." block.

However, if the section contains lots of one-liner text frames, then all
of them are masters, so the above code doesn't move them to the next
page; so the section frame is still not split. Fix the problem by
allowing the move of frames inside table-in-sections in
SwSectionFrame::MoveAllowed(), that way SwTextFrame::AdjustFrame() will
not set the text frame as undersized, so at the end
SwContentFrame::MakeAll() will call MoveFwd() in the "If a column
section can't find any space for its first ContentFrame" block.

With this the split of text frames in section-in-table frames is
consistent regardless if they are of multiple or single lines.

Change-Id: Ief9d62da3fd8a5c707e1f9489a92f7a81e7b38ac
Reviewed-on: https://gerrit.libreoffice.org/39623Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>