Fix build on OpenSolaris.

With these changes, dmd compiles on OpenSolaris 11.1.
Fix Issue 12678 - Field constness missing in diagnostics for multiple field initialization error.
Merge pull request #3512 from redstar/solaris

Fix build on OpenSolaris.
Merge pull request #3511 from AndrejMitrovic/Fix12678

Issue 12678 - Field constness missing in diagnostics for multiple field initialization error.
[style] fix indent
[Refactoring] Change return types from int to bool
[Refactoring] Remove side-effect in searchCtor
[Refactoring] Rename scope variable to `sc2` for aggregate members
Merge pull request #3513 from 9rnsr/refactor_ad

[Refactoring] Cleanup code around aggregates