The bugdoc has a single 1-column section from start to end, no
footnotes but lots of endnotes, and the section has the settings
"Footnotes - collect at end of text" unchecked and "Endnotes - collect
at end of section" checked.

This means that the SwFootnoteContFrame for footnotes would be put
directly below the SwPageFrame (so that multiple sections on a single
page can share it), but the SwFootnoteContFrame for the endnotes is
put below the SwColumnFrame (which is created despite only 1 column)
below the SwSectionFrame.

Hence content in endnotes has the mbInfSct flag set, and the crash
happens because the endnotes are moved from below the SwSectionFrame to
a new SwFootnoteContFrame that is directly below a SwPageFrame, without
clearing the mbInfSct flag.

Fix the wrong call in SwFootnoteBossFrame::MoveFootnotes_() to
FindFootnoteBossFrame() that resulted in the wrong (unsuitable for
endnotes) SwFootnoteContFrame to be used as the target for the move.

Change-Id: I64f6b86441e5ac1f16433f005e97c274a1c69dfa