Delete pre-generated sources

Having them here is confusing, and they can always be taken a
look at in the repo at
https://github.com/codeanticode/gstreamer-1.x-java
Temporarily work around JNAerator issue #511

https://github.com/ochafik/nativelibs4java/issues/511
Have the compile-tests build target depend on the all-in-one process
Remove jnaerator files and build targets for separate components

The current direction of work is to generate everything in one go,
using one single jnaerator file. Only the Linux build process is
affected, the macports specific jnaerator files are left untouched.