Go to a line breaking position near point by doing `kinsoku' processing.
LINEBEG is a buffer position we can't break a line before.
`Kinsoku' processing is to prohibit specific characters to be placed
at beginning of line or at end of line. Characters not to be placed
at beginning and end of line have character category `>' and `<'
respectively. This restriction is dissolved by making a line longer or
shorter.
`Kinsoku' is a Japanese word which originally means ordering to stay
in one place, and is used for the text processing described above in
the context of text formatting.
(fn LINEBEG)