50d5441e2a commit added a regression when
using pipes with GDB, OpenOCD would appear to hang when exiting GDB.
This fixes that behaviour so we shutdown correctly.
Change-Id: I9b337c2bdd41b1966de1c7631118257afcbfa6bd
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/993
Tested-by: jenkins