Add a bit-level transfer queue

Add a bit-level transfer queue

Interface drivers regularly need to keep track of where each part of a long
read buffer should be copied, once that data arrives. Both source and
destination are often at an arbitrary bit offset.

This queued bit-level copy can help with that, by allowing the driver to
perform postponed reads from the receive buffer already when building the
transmit buffer, and have those reads executed at a later time when data is
available.

For simplicity, it uses the linked list implementation list.h imported from
the Linux kernel.

Change-Id: I06862a0a6f057cbbcacfb021f17a795195faded2
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/450
Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>
Reviewed-by: Peter Stuge <peter@stuge.se>