Merge pull request #1474 from hamishknight/tbd-next

[master-next] lldb: repair the Windows build after #1447

Author: hamishknight

lldb/include/lldb/Symbol/SwiftASTContext.h

@@ -51,7 +51,7 @@ class IRGenOptions;
 class NominalTypeDecl;
 class SearchPathOptions;
 class SILModule;
-class TBDGenOptions;
+struct TBDGenOptions;
 class VarDecl;
 class ModuleDecl;
 class SourceFile;