debuggerd: fix missed use of ptrace(PTRACE_ATTACH). am: 8b6b654a5f am: fe59793375 am: 073f731836 am: 647ec18a9d  -s ours am: 364188b9d8
am: a200a4d592

Change-Id: Id5eb70bcb63b7fd4926baf2f738739a651dda27f