[NFC] Add a leading comment to boolean arguments. (#131746)

Addressing [nit comments](#129982 (comment)) from @shafik

Author: mpark

clang/lib/Serialization/ASTReader.cpp

@@ -10825,7 +10825,8 @@ void ASTReader::FinishedDeserializing() {
     {
       // Guard variable to avoid recursively entering the process of passing
       // decls to consumer.
-      SaveAndRestore GuardPassingDeclsToConsumer(CanPassDeclsToConsumer, false);
+      SaveAndRestore GuardPassingDeclsToConsumer(CanPassDeclsToConsumer,
+                                                 /*NewValue=*/false);
 
       // Propagate exception specification and deduced type updates along
       // redeclaration chains.

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -4314,7 +4314,8 @@ void ASTReader::PassInterestingDeclsToConsumer() {
 
   // Guard variable to avoid recursively redoing the process of passing
   // decls to consumer.
-  SaveAndRestore GuardPassingDeclsToConsumer(CanPassDeclsToConsumer, false);
+  SaveAndRestore GuardPassingDeclsToConsumer(CanPassDeclsToConsumer,
+                                             /*NewValue=*/false);
 
   // Ensure that we've loaded all potentially-interesting declarations
   // that need to be eagerly loaded.