Go request registration should be removed before C request memory freed.
C request address used as a key in Go map. Freed memory can be instantly
reused for other request and older request registration should removed at this
point to avoid collisions.
This allows to use shared memory to communicate with main process.
This patch changes shared memory segment format and breaks compatibility
with older modules.
Do not reuse shared memory segment with different port until this segment
successfully received and indexed on other side. However, segment can be used
to transfer data via the port it was sent at any time.
