Fix leaks in ComputeResourceInfo (XML parsing and test)

[FedeMPouzols]

This fixes #11467, memory leaks that valgrid detected.

To test:

• double check that tests passed
• code review

[FedeMPouzols]

In the last build everything went fine, except that SystemTests.CodeConventions complains about an unrelated algorithm. So despite the red cross I'd say this is ready for testing.

[FedeMPouzols]

Jenkins, retest this please

[FedeMPouzols]

Jenkins, wake up and retest this please

[stuartcampbell]

@FedeMPouzols I presume you haven't seen @rosswhitfield comments on slack - the old plugin is now disabled so the retest this type comments won't work anymore. You can either restart the job on jenkins directly or they will trigger with any new code changes.

[FedeMPouzols]

Jenkins, retest this please

[peterfpeterson]

I merged master back into the branch to kick off a new round of builds

[FedeMPouzols]

Good, thanks! One of them was definitely stuck since yesterday.

[eXeC64]

The only change has been to the ComputeResourceInfo unit test, which has no passed on all platforms. I'm not going to bother to wait for RHEL7 or Windows to finish as any failures that occur can only be random and unrelated.

Reviewed the code and it looks good to me.