I got the solution by using gmake.

With make (with my config.), the functions objects are 
written in the current directory. This means for example
url.c is not stored in the functions subdir and therefor 
the linking stage get an error.

Solution would be either to make a short Makefile in the 
functions subdir (which seems to me the most clean), of
making a subdepency which would first change directory to
functions to compile them.

Ph.R.