linux.execve64 test is flaky due to output reordering

http://build.chromium.org/p/client.dynamorio/builders/linux-dr/builds/756

debug-internal-64: 164 tests passed, ***\* 1 tests failed: ****
code_api|linux.execve64

21: parent is running under DynamoRIO
21: child is running under DynamoRIO
21: parent waiting for child
21: it_worked
21: child has exited
22/165 Test #21: code_api|linux.execve64 ................................***Failed Required regular expression not found.Regex=[^parent is running under DynamoRIO
parent waiting for child
child is running under DynamoRIO
it_worked
child has exited
$

So we have output reordering. Flaky test?

Start with the code_api|linux.execve64 test and the linked Linux build log, then inspect how its expected output is checked. Compare the observed and expected line ordering; done means the test reliably passes without rejecting valid process-output ordering.

Written by the indexing model from the issue text.