Correct OpenOCD version in tools.openocd.path definition

http://downloads.arduino.cc/packages/package_index.json specifies
openocd version 0.9.0-arduino6-static in the Arduino SAMD Boards 1.6.13
entry. The incorrect version previously used to define
tools.openocd.path caused uploads for SAMD boards to fail:
"java.io.IOException: Cannot run program
"{runtime.tools.openocd-0.9.0-arduino5-static.path}/bin/openocd.exe":
CreateProcess error=2, The system cannot find the file specified"