RequirementMachine: Split off RuleBuilder.{cpp,h} from RequirementLowering.{cpp,h}

Author: slavapestov

lib/AST/CMakeLists.txt

@@ -95,6 +95,7 @@ add_swift_host_library(swiftAST STATIC
   RequirementMachine/RewriteLoop.cpp
   RequirementMachine/RewriteSystem.cpp
   RequirementMachine/Rule.cpp
+  RequirementMachine/RuleBuilder.cpp
   RequirementMachine/SimplifySubstitutions.cpp
   RequirementMachine/Symbol.cpp
   RequirementMachine/Term.cpp

lib/AST/RequirementMachine/ConcreteTypeWitness.cpp

@@ -24,6 +24,7 @@
 #include <vector>
 #include "PropertyMap.h"
 #include "RequirementLowering.h"
+#include "RuleBuilder.h"
 
 using namespace swift;
 using namespace rewriting;