IrDsymbol::DModule is not used
Make IrDsymbol to be a typesafe union to reduce memory usage
Reduce size of IrDsymbol even more

resolved/defined/declared/initialized are turned into flags.
[Refactoring] Turn IrDsymbol flags into an enum value
Const and immutable fields with initializers are not globals since 2.064
Merge pull request #707 from AlexeyProkhin/IrDsymbol

Reduce the size of IrDsymbol struct