Simplify the error message for ABI check

- Remove "VNDK" from the message.
- Deprecate -elf-unreferenced-symbol-errors.
- Fix the status string for CompatibilityStatusIR::UnreferencedChanges.

Test: ./test.py
Bug: 249324120
Change-Id: I5a1fd64f9101caa29d87d9f65bd4d17b8bd77059
1 file changed