[Serialization] Rename "alias name type" to "builtin alias type".

We still use the old layout for NameAliasType for builtin types, so
rename the Layout struct and corresponding code to describe its new
(more restricted) purpose.

include/swift/Serialization/DeclTypeRecordNodes.def

@@ -78,7 +78,7 @@
 
 // These IDs must \em not be renumbered or reordered without incrementing
 // VERSION_MAJOR in ModuleFormat.h. Names, however, may change.
-FIRST_TYPE(NAME_ALIAS, 1)
+FIRST_TYPE(BUILTIN_ALIAS, 1)
 TYPE(GENERIC_TYPE_PARAM)
 TYPE(DEPENDENT_MEMBER)
 TYPE(NOMINAL)

include/swift/Serialization/ModuleFormat.h

@@ -641,8 +641,8 @@ namespace decls_block {
 #include "swift/Serialization/DeclTypeRecordNodes.def"
   };
 
-  using NameAliasTypeLayout = BCRecordLayout<
-    NAME_ALIAS_TYPE,
+  using BuiltinAliasTypeLayout = BCRecordLayout<
+    BUILTIN_ALIAS_TYPE,
     DeclIDField, // typealias decl
     TypeIDField  // canonical type (a fallback)
   >;

lib/Serialization/Deserialization.cpp

@@ -4145,11 +4145,11 @@ Expected<Type> ModuleFile::getTypeChecked(TypeID TID) {
     s->getFrontendCounters().NumTypesDeserialized++;
 
   switch (recordID) {
-  case decls_block::NAME_ALIAS_TYPE: {
+  case decls_block::BUILTIN_ALIAS_TYPE: {
     DeclID underlyingID;
     TypeID canonicalTypeID;
-    decls_block::NameAliasTypeLayout::readRecord(scratch, underlyingID,
-                                                 canonicalTypeID);
+    decls_block::BuiltinAliasTypeLayout::readRecord(scratch, underlyingID,
+                                                    canonicalTypeID);
     auto aliasOrError = getDeclChecked(underlyingID);
     if (!aliasOrError)
       return aliasOrError.takeError();

lib/Serialization/Serialization.cpp

@@ -3597,12 +3597,12 @@ void Serializer::writeType(Type ty) {
     TypeAliasDecl *typeAlias =
       findTypeAliasForBuiltin(M->getASTContext(), ty);
 
-    unsigned abbrCode = DeclTypeAbbrCodes[NameAliasTypeLayout::Code];
-    NameAliasTypeLayout::emitRecord(Out, ScratchRecord, abbrCode,
-                                    addDeclRef(typeAlias,
-                                               /*forceSerialization*/false,
-                                               /*allowTypeAliasXRef*/true),
-                                    TypeID());
+    unsigned abbrCode = DeclTypeAbbrCodes[BuiltinAliasTypeLayout::Code];
+    BuiltinAliasTypeLayout::emitRecord(Out, ScratchRecord, abbrCode,
+                                       addDeclRef(typeAlias,
+                                                  /*forceSerialization*/false,
+                                                  /*allowTypeAliasXRef*/true),
+                                       TypeID());
     break;
   }
   case TypeKind::BoundNameAlias: {
@@ -3977,7 +3977,7 @@ void Serializer::writeType(Type ty) {
 void Serializer::writeAllDeclsAndTypes() {
   BCBlockRAII restoreBlock(Out, DECLS_AND_TYPES_BLOCK_ID, 8);
   using namespace decls_block;
-  registerDeclTypeAbbr<NameAliasTypeLayout>();
+  registerDeclTypeAbbr<BuiltinAliasTypeLayout>();
   registerDeclTypeAbbr<BoundNameAliasTypeLayout>();
   registerDeclTypeAbbr<GenericTypeParamDeclLayout>();
   registerDeclTypeAbbr<AssociatedTypeDeclLayout>();