[mlir] Provide defaults to make enabling dumping simpler

[jpienaar]

Summary

This adds some default values to enableIRPrinting so that it is simpler to enable it for a given pass manager. I kept on finding myself duplicating pretty much this call every time I wanted to do a quick debug run.

mlir/include/mlir/Pass/PassManager.h

 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator.h"
 
 #include <functional>
 #include <vector>
 
 namespace llvm {
 class Any;
+raw_ostream &errs();
 } // end namespace llvm
 
 namespace mlir {
 class AnalysisManager;
 class MLIRContext;
 class ModuleOp;
 class OperationName;
 class Operation;
public:
   ///   return true if the IR should be printed or not.
   /// * 'printModuleScope' signals if the module IR should be printed, even
   ///   for non module passes.
   /// * 'printAfterOnlyOnChange' signals that when printing the IR after a
   ///   pass, in the case of a non-failure, we should first check if any
   ///   potential mutations were made.
   /// * 'out' corresponds to the stream to output the printed IR to.
   void enableIRPrinting(
-      std::function<bool(Pass *, Operation *)> shouldPrintBeforePass,
-      std::function<bool(Pass *, Operation *)> shouldPrintAfterPass,
-      bool printModuleScope, bool printAfterOnlyOnChange, raw_ostream &out);
+      std::function<bool(Pass *, Operation *)> shouldPrintBeforePass =
+          [](Pass *, Operation *) { return true; },
+      std::function<bool(Pass *, Operation *)> shouldPrintAfterPass =
+          [](Pass *, Operation *) { return true; },
+      bool printModuleScope = true, bool printAfterOnlyOnChange = true,
+      raw_ostream &out = llvm::errs());
 
   //===--------------------------------------------------------------------===//
   // Pass Timing
 
   /// A configuration struct provided to the pass timing feature.
   class PassTimingConfig {
   public:
     using PrintCallbackFn = function_ref<void(raw_ostream &)>;