message: Add a setAttrList() method on mlir::Operation
  This is an efficient method to copy attributes from one operation to
  another.
diff: @@ -257,6 +257,11 @@ public:
  /// Return the internal attribute list on this operation.
  NamedAttributeList &getAttrList() { return attrs; }
  + /// Set the attribute list on this operation.
  + /// Using a NamedAttributeList is more efficient as it does not require new
  + /// uniquing in the MLIRContext.
  + void setAttrList(NamedAttributeList newAttrs) { attrs = newAttrs; }
  +
  /// Return the specified attribute if present, null otherwise.
  Attribute getAttr(Identifier name) { return attrs.get(name); }
  Attribute getAttr(StringRef name) { return attrs.get(name); }
  