functions: allow using sub-dir of a module

Some projects' module (eg. newlib) are checked-out into a sudirectory
rather than into their own directory. Handle this case in the CT_GetCVS
function.

 reporter_name="Julien DUSSER"

 reporter_url="http://sourceware.org/ml/crossgcc/2008-10/msg00054.html"

 reporter_comment="Soft-float for the 405 PowerPC"