The count value can be used to batch timeouts. I.e., if a periodic
timeout triggered multiple times before the timer had a chance to
process them, the count corresponds to the number of passed periods.
Depending on 'src_w' and 'dst_w', different lines of a block to copy may be
32-bit aligned or not, so the alignment of each line needs to get checked.
Fixes#1111.
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
