...on macOS with case-insensitive file systems.  When compiling e.g.
workdir/UnpackedTarball/liborcus/src/parser/base64.cpp, libtool adds -I../..
(presumably to find files like workdir/UnpackedTarball/liborcus/config.h), and
including e.g. <vector> internally includes <version> now, and
workdir/UnpackedTarball/liborcus/VERSION (generated from VERSION.in) happens to
win.  So disable generation of VERSION from VERSION.in (Kohei confirmed in
private communication that that file isn't actually used for anything, so not
generating it is fine).  (An alternative approach might have been to use
-iquote../.. instead of -I../.., but that's probably hard to shoehorn into the
libtool-generated compiler invocation.)

Change-Id: Id9a6778368796dc2494df3499b5e1ca560df1e56
Reviewed-on: https://gerrit.libreoffice.org/61358Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Jenkins