Improve XML test results collector.

Improve XML test results collector.

[Issue#]       N/A
[Bug]          testsuite tag attributes are not filled out when
segmentation fault occurs
[Cause]        values of those attributes are filled out at the end of a
successful run of a test binary
[Solution]     update attributes values after each test case
[Verification]
1. Build repository
2. Run wrt-tests-misc test suite with output set to xml and text
  `wrt-tests-misc --output=xml --output=text`
3. Compare results
4. Check whether file results.xml is a valid XML document.

Change-Id: Ic3c5fa0b3ce6b943cf1ac949b3313d436ed4f8b0