fix funny build issue by not linking plugin libraries to gstreamer core. this is...

fix funny build issue by not linking plugin libraries to gstreamer core. this is because they are plugins, not shared...

Original commit message from CVS:
fix funny build issue by not linking plugin libraries to gstreamer core. this is
because they are plugins, not shared libraries per se, and will only be loaded by
the core itself. this change allows the core elements (schedulers, autopluggers, etc)
to use the core loadable libraries (bytestream, getbits, etc) as well as "ext" libs
like the new cothreads package.