Tweak shared libraries more:

  * Add a few more SHARED_LIBS, and move them to -talloc;
  * Install symlinks in ${PREFIX}/lib for those libraries, to make
    ports using our libtool to reach them (audio/rhythmbox);
  * Rename -talloc to -util, saving version of libtalloc (questionable).

The reason is that some utility libraries depend on libtalloc, and
libtalloc in turn depends on some of them. There is no reason to
split those.

Now all ports depending on different Samba parts could build with
Samba4.