[ORC] Loosen __objc_imageinfo flag merging to match ld (#91767)

Allow mixing objects with/without signed class ro data and category
class properties as long as it happens before we register the metadata.
These combinations are a warning in ld, not a hard error. The only case
that is ABI-breaking is if we already registered with the feature
enabled but later try to load an object that doesn't support it.

rdar://127336061