Fix VM_GAHP_DEBUG to work properly.

The vm-gahp's attempt to add D_PID to the debug flags was causing it to
ignore other flags set in the config file.
Fix directory permissions for Xen/KVM VM universe jobs. #3781

The vm-gahp issues libvirt commands as root. Libvirt fails if root
doesn't have explicit permission to access the disk image files.
Therefore, we need to relax the normal execute directory permissions
from 700 to 755.