audioprocessing: fix cmake

+ Adds some missing references to the recently added files.
+ Removes the include of 'speex_config_types.h' on native Windows.

TODO: Refactor the cmake to be in one file. Way too complicated for
nothing. Also, "source_group" is probably not used by most devs.

Change-Id: I020caf40544d2a7502c70d96fec99b08278ac2ff