cmake: add export_complex_library function

parameters LIBNAME and MODULE (module)

* adds LIBNAME to a global property ${${MODULE}_EXPORTS}
* if MODULE isn't given LIBNAME is expected to be in the format
  "module-libname"
cmake: add_complex_library add EXPORT parameter

EXPORT is an optional parameter. If set the module is also
marked for export.
cmake: remove debug message
audin/client/alsa: fix installation path

The module was installed into the libdir instead of addin path.
export_complex_library add support for long names

If no MODULE is given the first part of LIBNAME is used as module.
The expected format is still MODULE-LIBNAME but now LIBNAME can also
contain -.
cmake: mark required libraries for export
update and improve pkg-config files

* generate pkg-config files top level to make sure all
  exports are available (eg. client/server)
* .pc libs section is now generated from export libraries
* update .pc file to use .private fields (prevent overlinking)
Merge pull request #1806 from bmiklautz/feat/export_modules

Improve pkg-config file generation