Forbid overriding property definitions via inheritance
Forbid overriding property definitions via inheritance

The previous language disallowed overriding properties in derived
property sets but allowed for it via multiple inheritance, thus doing a
poor job enforcing the intent that properties are aggregated, not
overridden.

Correct the language to explicitly disallow overriding property
definitions. Include a practical exception allowing identical property
definitions in multiple base property sets.

Signed-off-by: Darren Hart <38f9eaa30910c40b06f5a60020b1222f2a953801@infradead.org>

ahs3/dsd