old_version is not transported to lib-src/Makefile

[Norbert Koch <nk@xxxxxxxxxx>]

Hi!

I've just noticed that the value of old_version is set only in the top
level Makefile, but not in lib-src/Makefile (resp in GNUmakefile).
Thus, a make install results in a $prefix/sxemacs-/... directory (on
my machine at least).

I'm absolutely clueless where to tweak things in order to get this
fixed :-/

Regards,
norbert.