Fix using Definitions as arguments to Definitions (#3726)

(cherry picked from commit a050b8cd)

# Conflicts:
#	core/src/main/scala/chisel3/Module.scala
#	core/src/main/scala/chisel3/experimental/hierarchy/Definition.scala
#	core/src/main/scala/chisel3/experimental/hierarchy/Instance.scala
#	core/src/main/scala/chisel3/internal/Builder.scala
#	src/main/scala/chisel3/aop/injecting/InjectingAspect.scala
#	src/main/scala/chisel3/stage/phases/Elaborate.scala