MFstable/10 r294063:

MFC r293028,r293029:

r293028:

• Use geom <class> load instead of g<class> load; g<class> doesn't exist for all geom classes, e.g. geom_uzip(4)
• These tests require root. Skip all of the tests if they're run as non-root

r293029:

Add functions for managing md(4) devices and cleaning up said md(4) devices

These will be used soon in the various test scripts that source geom_subr.sh