ModuleInterface: Print imports with @preconcurrency in swiftinterface files.

When a module has been imported `@preconcurrency` in source, when it is printed
in a `swiftinterface` file it should be printed along with the attribute to
ensure that type checking of the module's public declarations behaves
consistently.

This fix is a little unsatisfying because it adds another a linear scan over
all imports in the source for each printed import. This should be improved, but
it can be done later.

Resolves rdar://136857313.

lib/Serialization/SerializedModuleLoader.cpp

@@ -1915,6 +1915,14 @@ void SerializedASTFile::lookupImportedSPIGroups(
   }
 }
 
+bool SerializedASTFile::isModuleImportedPreconcurrency(
+    const ModuleDecl *importedModule) const {
+  // This method should only be queried during `-merge-modules` jobs, which are
+  // deprecated, and thus no effort has been made to answer this query correctly
+  // (@preconcurrency is not encoded on imports in serialized modules).
+  return false;
+}
+
 std::optional<CommentInfo>
 SerializedASTFile::getCommentForDecl(const Decl *D) const {
   return File.getCommentForDecl(D);