crosperf: keep alive if one machine is down.

Originally, crosperf dies if any of machine in the machine list is
unreachable, this patch just ignore the unreachable machine.

BUG=None
TEST=crosperf a simple testcase passes.

Change-Id: I835b484f5378215da142d5e8e64471ce744aea30
Reviewed-on: https://gerrit-int.chromium.org/38475
Reviewed-by: Luis Lozano <llozano@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@google.com>
Tested-by: Yunlian Jiang <yunlian@google.com>
1 file changed