Split run_tool.py into run_tool.py, extract_edits.py and apply_edits.py

tools/clang/translation_unit/TranslationUnitGenerator.cpp

Index: tools/clang/translation_unit/TranslationUnitGenerator.cpp
diff --git a/tools/clang/translation_unit/TranslationUnitGenerator.cpp b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
index 4d7524d90ab544b68ac4daa7028d321dbb13998c..e6be43e5033e74aef00685c18c417bcda5f3b266 100644
--- a/tools/clang/translation_unit/TranslationUnitGenerator.cpp
+++ b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
@@ -265,9 +265,5 @@ int main(int argc, const char* argv[]) {
       clang::tooling::newFrontendActionFactory<CompilationIndexerAction>();
   clang::tooling::ClangTool tool(options.getCompilations(),
                                  options.getSourcePathList());
-  // This clang tool does not actually produce edits, but run_tool.py expects
-  // this. So we just print an empty edit block.
-  llvm::outs() << "==== BEGIN EDITS ====\n";
-  llvm::outs() << "==== END EDITS ====\n";
   return tool.run(frontend_factory.get());
 }