For example needed for underscores which are removed by VCL=gtk3 when
interpreted as mnemonics.
Change-Id: Ic80b64efc81ab5a219b1db1395974a4b59c46833
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/171497
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>