Fix : libcanfestival_unix.a not built if examples are not compiled

Problem: when building Canfestival with unix timers 'libcanfestiva_unix.a'
is built only if you build examples too.

Test case:

$ ./configure --timers=unix --can=socket --target=unix
$ make canfestival

...

no errors but 'libcanfestival_unix.a' is not built:
$ find . -name "*.a"
./src/libcanfestival.a

Changing line 90 of 'drivers/unix/Makefile.in' to:
#driver: $(OBJS)
driver: libcanfestival_$(TARGET).a

solves the problem:

$ ./configure --timers=unix --can=socket --target=unix
$ make canfestival

...

$ find . -name "*.a"
./drivers/unix/libcanfestival_unix.a
./src/libcanfestival.a

SillySlave example for CANfestival

Its purpose is only to check if the selected
driver works at least a minimum. The PC running this demo
must be connected through CAN bus to a working master that 
recognizes the slave nodeId. The slave should be configured
by the master, then switched to operative. After that, when
the master sends a SYNC, the slave answers with PDO1, 
containing an integer that increments each time it is sent.

Please have a look to main.h to tune the master and slave node IDs

It's all. Enjoy it.
GMB
jan 17,2008