Sweep different parameter sets in a single shell script.

test/cpp/qps/qps-sweep.sh

+#!/bin/sh
+
+if [ x"$QPS_WORKERS" == x ]; then
+  echo Error: Must set QPS_WORKERS variable in form \
+    "host:port,host:port,..." 1>&2
+  exit 1
+fi
+
+bins=`find . .. ../.. ../../.. -name bins | head -1`
+
+for channels in 1 2 4 8
+do
+  for client in SYNCHRONOUS_CLIENT ASYNC_CLIENT
+  do
+    for server in SYNCHRONOUS_SERVER ASYNC_SERVER
+    do
+      for rpc in UNARY STREAMING
+      do
+        echo "Test $rpc $client $server , $channels channels"
+        "$bins"/opt/qps_driver --rpc_type=$rpc \
+          --client_type=$client --server_type=$server
+      done
+    done
+  done
+done