Use the KWSys Process "MergeOutput" option to give each test child
process the same pipe for both stdout and stderr. This allows natural
merging of stdout and stderr together instead of merging on arbitrary
buffered read boundaries as before.
When matching ctest command-line output, we must account for the
formatting of times that take 10 seconds or more. The values are
right-justified, so use " +" to match any amount of space before them.