* pppd/Makefile.am: Use .$(OBJEXT) instead of .o.
* rtems_servers/Makefile.am: Use .$(OBJEXT) instead of .o.
* rtems_telnetd/Makefile.am: Use .$(OBJEXT) instead of .o.
* rtems_webserver/Makefile.am: Use .$(OBJEXT) instead of .o.
* wrapup/Makefile.am: Use .$(OBJEXT) instead of .o.