No arch is using this anymore, and we want all new ports using the
hardware framework instead. Punt WITH_DEVICES and the two callbacks
device_io_{read,write}_buffer.
We can also punt the tconfig.h file as no port is using it anymore.
This fixes in-tree builds that get confused by picking up the wrong
one (common/ vs <port>/) caused by commit ae7d0cac8c.
Any port that needs to set up a global define can use their own
sim-main.h file that they must provide regardless.
Rather than manually include tconfig.h when we think we'll need it (which
is error prone as it can define symbols we expect from config.h), have it
be included directly by config.h. Since we know we have to include that
header everywhere already, this will make sure tconfig.h isn't missed.
It should also be fine as tconfig.h is supposed to be simple and only set
up a few core defines for the target.
This allows us to stop symlinking it in place all the time and just use
it straight out of the respective source directory.
Mike Frysinger
Roland McGrath
Nick Clifton