mkdumprd doesn't detect /var mounted on separate partion and kdump fails.

Issue

• On our system /var is a separate parition. Under RHEL6, the mkdumprd utility correctly detects this on the live system (without needing entries in /etc/kdump.conf) and builds a kdump initrd that mounts the /var patition and dumps to /crash on that parition.
• RHEL5 does not do this. The kdump initrd fails to save the core file because it is incorrectly looking for /var/crash on the root filesystem, and it isn't there. It eventually panics the kdump kernel.