veyron/lib/exec: Fix panic in handle.Clean()

Fixes a panic in handle.Clean() when Start() fails.

panic: runtime error: invalid memory address or nil pointer dereference
[...]
Feb 06 11:19:07 rpi001 agent_deviced.sh[419]: v.io/core/veyron/lib/exec.(*ParentHandle).Kill(0x15dfdd80, 0x0, 0x0)
Feb 06 11:19:07 rpi001 agent_deviced.sh[419]: /home/rthellend/vanadium/release/go/src/v.io/core/veyron/lib/exec/parent.go:324 +0x38
Feb 06 11:19:07 rpi001 agent_deviced.sh[419]: v.io/core/veyron/lib/exec.(*ParentHandle).Clean(0x15dfdd80, 0x0, 0x0)
Feb 06 11:19:07 rpi001 agent_deviced.sh[419]: /home/rthellend/vanadium/release/go/src/v.io/core/veyron/lib/exec/parent.go:334 +0x30

Change-Id: I86488b3effaccfa82c086baea10f1dee256efbde
1 file changed
tree: ade8bef776c2a16f1c588161f9f9ee155776c7f6
  1. lib/
  2. profiles/
  3. runtimes/
  4. security/
  5. services/
  6. tools/