Issue 10514 - Constructor declaration grammar is incorrect

https://d.puremagic.com/issues/show_bug.cgi?id=10514

Same issue is in `ConstructorTemplate`, `Destructor`, `Postblit`, `Allocator`, `Deallocator`,
`StaticConstructor`, `StaticDestructor`, `SharedStaticConstructor`, and `SharedStaticDestructor`.