[ClangImporter] don't add swift_attr files to a module's auxiliary files (#65867)

rdar://107624995

Author: QuietMisdreavus

lib/ClangImporter/ImportDecl.cpp

@@ -7561,7 +7561,6 @@ SourceFile &ClangImporter::Implementation::getClangSwiftAttrSourceFile(
   auto sourceFile = new (SwiftContext) SourceFile(
       module, SourceFileKind::Library, None);
   ClangSwiftAttrSourceFiles.insert({&module, sourceFile});
-  module.addAuxiliaryFile(*sourceFile);
   return *sourceFile;
 }
 

test/SymbolGraph/ClangImporter/SwiftAttrExtension.swift

@@ -0,0 +1,28 @@
+// REQUIRES: objc_interop
+
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/SwiftAttr)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-module -emit-module-path %t/SwiftAttrExtension.swiftmodule -enable-objc-interop -I %t/SwiftAttr -module-name SwiftAttrExtension -emit-symbol-graph -emit-symbol-graph-dir %t %t/Extension.swift
+// RUN: %FileCheck %s --input-file %t/[email protected]
+
+//--- SwiftAttr/module.modulemap
+module SwiftAttr {
+  header "SwiftAttr.h"
+}
+
+//--- SwiftAttr/SwiftAttr.h
+@import Foundation;
+
+__attribute__((swift_attr("@_nonSendable(_assumed)")))
+@interface MyObjcClass : NSObject
+@end
+
+//--- Extension.swift
+import SwiftAttr
+
+extension MyObjcClass {
+  // CHECK: s:So11MyObjcClassC18SwiftAttrExtensionE8someFuncyyF
+  public func someFunc() {}
+}