Modify to help better support HHVM

We are testing HHVM against many different frameworks to improve its parity with Zend. With respect to Pear, we are failing some tests with different error messages. HHVM uses some error messages that were around pre-Zend 5.x. For many tests, I added a check for HHVM that allows the use of these older error messages.

In addition, I also found some tests that were failing both HHVM and Zend 5.5 and modified them so that they would pass, particularly around the omission of a sha1sum in XML output. 

On a side not, I have a list of many tests that fail both Zend 5.5 and HHVM. I haven't had a chance to try to fix them all. Here is another one for an example:

pear-core/tests/PEAR_PackageFile_v2_Validator/test_contents.phpt

I was thinking of providing you the full list in a GitHub issue, but I don't think Issues are enabled for this repository. Let me know if you are interested in this list.