LP1874510 libopensrf recv timeout cal repair

LP1874510 libopensrf recv timeout cal repair

Fixes the message receive timeout calculation logic in OpenSRF C client
code.  The calculation is performed when multiple calls to receive are
needed to piece together a response message.

The logic previously calculated the time remaining as the time remaining
minus the total time taken for all iterations with each loop iteration,
leading to exhausting the timeout too quickly.  Now it calculates the
value as time remaining minus the time taken for the only most recent
loop iteration.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Jason Stephenson <jason@sigio.com>