Fix test_prctl so that it does not leave behind a stopped process
Fix test_prctl so that it does not leave behind a stopped process

The stuck process means that running tests over ssh causes ssh to hang
when the tests are finished, because ssh never gets EOF from stdout.

The problem was apparently that PTRACE_KILL does not kill the
subprocess unless you have cleared the wait status queue for the
subprocess first.

Review URL: http://codereview.chromium.org/3363006

git-svn-id: c2a6f690695ec6703fa4e0d44c2dfcc6697c486d@102 55e79e8e-603c-11de-8c10-5fe6993ea61f

mseaborn/seccompsandbox,mseaborn/seccompsandbox,mseaborn/seccompsandbox