[Swiftify] Skip swiftify during symbolic import (#81349)

Swiftify cannot work in this mode. This mode has been removed entirely
in main. This takes a smaller change into the release to minimise risk.

rdar://149953125

Author: hnrklssn

lib/ClangImporter/ImportDecl.cpp

@@ -9097,6 +9097,8 @@ class SwiftifyInfoPrinter {
 void ClangImporter::Implementation::swiftify(FuncDecl *MappedDecl) {
   if (!SwiftContext.LangOpts.hasFeature(Feature::SafeInteropWrappers))
     return;
+  if (importSymbolicCXXDecls)
+    return;
   auto ClangDecl =
       dyn_cast_or_null<clang::FunctionDecl>(MappedDecl->getClangDecl());
   if (!ClangDecl)