device filtering support

[Michael Plante]

Xiaofan Chen wrote:
>> I do not know if the following replacement from OpenOCD can
>> be a start point or not.
>>
http://openocd.git.sourceforge.net/git/gitweb.cgi?p=openocd/openocd;a=blob;f
=src/helper/replacements.c;hb=HEAD


That probably depends on a few things:

1. Are we even using fds?  If so, would we if we had a choice?

2. Do we really want to go with a timeslice (busy-wait) method?

3. Is it necessarily our job to expose an API that allows non-USB
   wait objects to be added?  If not, our wait function could be
   much less general.  Sample code, of course, might not be.

Regards,
Michael