RequirementMachine: Split off nested type concretization from PropertyUnification.cpp to ConcreteTypeWitness.cpp

Author: slavapestov

lib/AST/CMakeLists.txt

@@ -74,6 +74,7 @@ add_swift_host_library(swiftAST STATIC
   ProtocolConformance.cpp
   RawComment.cpp
   RequirementEnvironment.cpp
+  RequirementMachine/ConcreteTypeWitness.cpp
   RequirementMachine/GenericSignatureQueries.cpp
   RequirementMachine/HomotopyReduction.cpp
   RequirementMachine/InterfaceType.cpp