fix const-ref with --dumpapi & --checkapi

--dumpapi dumps enumerator references as fully-qualified.
--checkapi compares const-expr values with their literals.
  : in checkapi mode, we don't resolve type/field references. So we
  can't evaluate const-ref values.

Bug: 142893595
Test: aidl_unittests
Change-Id: Ia564c227c0683c646b6f1654a0b9349125d4992b
3 files changed