Coverage now ignore phpunit ignores

phpunit segfault (bug 43972) which in turns prevents the Jenkins Clover
PHP Plugin from generating the coverage report. Workaround is to ignore
errors using shell trick '|| :'.

The Jenkins feature request to have coverage report to always run is:
 https://issues.jenkins-ci.org/browse/JENKINS-21046

Bug: 43972
Change-Id: I39ec04275b9695ddd2890425b6a50458382e80df