MB-10090 Fix receive_group_header buffered stdout reader method

receive_group_header method simulates blocked read of bytes in
given length by operating on the port interface in stream mode.
In stream mode, data is received as messages asynchronously.
If data accumulator received by this method is less than the
given length, it has to wait for data to arrive through port
and append to the existing data to extend the buffered data.

The current buffer was getting replaced by newly arrived data
rather than appending it and hence it indefinitely waits for
enough bytes to arrive. The test needs to use 1024 vbuckets
to go through this code path.

Change-Id: I757ecda73ac29ffba983aed64362cdf9b2f9914c
Reviewed-on: http://review.couchbase.org/33073
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: buildbot <build@couchbase.com>
MB-7629 Fix view compactor incremental progress stats

The native view compactor can now send intermediate
progress of how much kvs are written at every percentage
progress intervals.

Change-Id: I4c9ddbfee0b0531733552d54f2eb92a5fe44cf6b
Fix updater stats task to stay until disk write is complete

The the updater progress stats is populated from
the docloader when documents are loaded into MapQueue.
Even after all documents are loaded to MapQueue, it takes
additional amount of time to sort records and and build/update
ondisk indexes. Even though loading is complete, we need to make
sure that the progress stats task should not dissapear until
the whole updater processing is complete.

Change-Id: Idf3d3304d488a0bf3851db1b2b172ea6e796f1e0
Add support for stopping native index builder

Similar to the native compacter and native btree updater,
added ability to send a stop message to the index builder
and wait for native process to exit.

Change-Id: Ibda0ef728100266508407f6512f6f12dac2080d3
Remove sorting step for mapreduce initial index builder

Native btree index builder takes care of sorting before
the btree build. Hence sorting step is not required from
erlang side for mapreduce views.

Change-Id: Iafee54d0d65ca4c5cd90389d91e258792776989e