oeqa/utils/qemurunner.py: Be sure to stop qemu-system

When runqemu fails, qemu-system process would keep running
and won't be killed, setpgrp() was used when runqemu was
a shell script but it seems it doesn't work always with python.

This would kill qemu-system explicity and to avoid leaving
it behind.

(From OE-Core rev: 9d2b1aa1bcfb2f1933a8eeb9470b4174d5da2f0d)

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/testimage.bbclass

@@ -171,6 +171,8 @@ def testimage_main(d):
             bb.plain(msg)
         else:
             bb.fatal("%s - FAILED - check the task log and the ssh log" % pn)
+    except BlockingIOError as err:
+        bb.error('runqemu failed, shutting down...')
     finally:
         signal.signal(signal.SIGTERM, tc.origsigtermhandler)
         target.stop()