Instead of holding SPEC-variable dependent files and directories inline
within the repository structure, move them into 'spec' subdirectories
at the corresponding levels, e.g.:
repos/base/include/spec
repos/base/mk/spec
repos/base/lib/mk/spec
repos/base/src/core/spec
...
Moreover, this commit removes the 'platform' directories. That term was
used in an overloaded sense. All SPEC-relative 'platform' directories are
now named 'spec'. Other files, like for instance those related to the
kernel/architecture specific startup library, where moved from 'platform'
directories to explicit, more meaningful places like e.g.: 'src/lib/startup'.
Fix#1673
With the introducation of the Audio_in session interface it makes
sense to rename the current available audio drivers. At the moment
only the dde_bsd audio_drv supports Audio_out as well as Audio_in.
The Linux audio_drv only supports Audio_out (there is no demand for
Audio_in support currently) but is renamed nonetheless to make it
easiert to write generic run scripts.
Issue #1644.