[LyX/master] DocBook: use the right key when generating bibiomixed.

[Thibaut Cuvelier]

commit 53245660139e7c3cc0c5b2251bbc5513c21fdbff
Author: Thibaut Cuvelier <tcuvelier at lyx.org>
Date:   Sat Aug 1 03:37:25 2020 +0200

    DocBook: use the right key when generating bibiomixed.

 .../export/docbook/bibliography_precooked.xml      |    6 +-
 .../docbook/bibliography_precooked_aastex.lyx      | 2277 ++++++++++++++++++++
 .../docbook/bibliography_precooked_aastex.xml      | 1117 ++++++++++
 src/insets/InsetBibitem.cpp                        |    1 -
 src/output_docbook.cpp                             |    2 +-
 5 files changed, 3398 insertions(+), 5 deletions(-)