Just use --with-extra-buildid=Flatpak

...as suggested in comment <https://github.com/flathub/
org.libreoffice.LibreOffice/issues/48#issuecomment-399739393> to "LibreOffice
6.0.5": "Should 'Flatpak version' be just 'Flatpak' to save translation of
'version' in the string for non-English locales?"

Change-Id: I53171a5725f54520ae9e3cbaf294e291d16e1c78
Reviewed-on: https://gerrit.libreoffice.org/56390
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit 3a8ae607cb0e63f252ca5a3b224f479cf304dc3f)
Reviewed-on: https://gerrit.libreoffice.org/56403
diff --git a/distro-configs/LibreOfficeFlatpak.conf b/distro-configs/LibreOfficeFlatpak.conf
index 4440c3aa..10c767b 100644
--- a/distro-configs/LibreOfficeFlatpak.conf
+++ b/distro-configs/LibreOfficeFlatpak.conf
@@ -2,7 +2,7 @@
--disable-odk
--enable-release-build
--with-ant-home=/run/build/libreoffice/ant
--with-extra-buildid=Flatpak version
--with-extra-buildid=Flatpak
--with-jdk-home=/usr/lib/sdk/openjdk10/jvm/openjdk-10
--with-lang=ALL
--with-system-libs