kill gdbserver on device before start gdb test.

BUG=None
TEST=the process of gdbserver leader-exit.exp is gone.

Change-Id: Ifd7d47a7064275a16e1faf7faf03e6c1d281ff59
Reviewed-on: https://gerrit-int.chromium.org/37310
Commit-Queue: Yunlian Jiang <yunlian@google.com>
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Tested-by: Yunlian Jiang <yunlian@google.com>
1 file changed