Missing .pc files generated for gstadaptivedemux, gstphotography, basecamerabinsrc, gstisoff, gsturidownloader

Which means that building an android app is currently broken as the corresponding .la files are not generated by cerbero

2 options:

1. add .pc file for the libraries. I think these were not added as to avoid apps using them.
2. generate the necessary .la files manually in cerbero. Would also need fixing up later when we move to .pc files later as well.

Thoughts?