debuggerd: fix missed use of ptrace(PTRACE_ATTACH). am: 8b6b654a5f am: fe59793375 am: 073f731836 am: 647ec18a9d  -s ours am: 364188b9d8 am: faa7e41a7f
am: d982f121c3

Change-Id: I9356ea3f41f30b73bb1ce4cc9837046603b0cb7e