#5414 LyricExtender unduly shortened for end-of-line clef change

[Simon Albrecht]

If a LyricExtender crosses a line break and any system has a clef change at that line break, the pre-break part of the extender will be shortened, which looks odd and isn’t necessary.

\version "2.19.82"

\header { tagline = ##f }
\paper {
  #(set-paper-size "a8")
  indent = 0
}
<<
  { 1~ \break 1 }
  \addlyrics { test __ }
  { 8 8 8 8 8 8 8 8 \clef bass 1 }
>>