Blender Git Loki

In some directories (e.g. source/blender/src) there are so many files
now that the command to put the object files into an archive is
exceeding 20k characters, which is a problem for some operating systems.
To avoid this, this modification causes make to change directories before
archiving, to avoid having to specify full file paths to the files
being archived.

If this causes problems on some systems, let me know and I'll find an
alternative.