This removes a lot of unnecessary code that is generated by
the compiler automatically.
In very few cases, a defaulted destructor in a .cc file is
still necessary, because of forward declarations in the header.
I removed some defaulted virtual destructors, because they are not
necessary, when the parent class has a virtual destructor already.
Defaulted constructors are only necessary when there is another
constructor, but the class should still be default constructible.
Differential Revision: https://developer.blender.org/D10911
This will make it easier & cleaner to make custom-built depsgraph (for
example for exporting invisible objects to USD or Alembic, see T75936).
No functional changes.
Reviewed by: sergey
Differential Revision: https://developer.blender.org/D8423
