The unix time and network operations are going to be used as a fall-back
solution by other timing engines.

For example, hardware-specific timestamping capabilities can be
selected (such as the Linux ioctl API) but if the Ethernet interface
(and thus the pp_instance) doesn't support the feature, related code
will be able to set back the unix operations in place.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

The contents of this directory are pretty portable anyways, and
the internal files were actually called "posix-io.c" and so on.
So let's get rid of the too-politica "gnu-linux" naming and of
the too-little-political "posix" at the same time.  We build
on Unix roots, so let's call our architecture like that.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Aurelio Colosimo <aurelio@aureliocolosimo.it>