RequirementMachine: Don't record rewrite loops for protocol signature machines

A requirement machine built from existing protocol requirement signatures only
exists to cache those rules and allow them to be inherited by other machines.

Recording loops is unnecessary in this case, since no minimization will be
performed.

Author: slavapestov

lib/AST/RequirementMachine/RequirementMachine.cpp

@@ -90,7 +90,7 @@ RequirementMachine::initWithProtocolSignatureRequirements(
   builder.initWithProtocolSignatureRequirements(protos);
 
   // Add the initial set of rewrite rules to the rewrite system.
-  System.initialize(/*recordLoops=*/true, protos,
+  System.initialize(/*recordLoops=*/false, protos,
                     std::move(builder.WrittenRequirements),
                     std::move(builder.ImportedRules),
                     std::move(builder.PermanentRules),