Fix typo in HashBuild operator (facebookincubator#11234)

Summary: Pull Request resolved: facebookincubator#11234

Reviewed By: amitkdutta

Differential Revision: D64417820

Pulled By: kgpai

fbshipit-source-id: ea22782b4cb3cd36beff7d43e43296db75d7ba2d

velox/exec/HashBuild.cpp

@@ -73,7 +73,7 @@ HashBuild::HashBuild(
 
   joinBridge_->addBuilder();
 
-  auto inputType = joinNode_->sources()[1]->outputType();
+  const auto& inputType = joinNode_->sources()[1]->outputType();
 
   const auto numKeys = joinNode_->rightKeys().size();
   keyChannels_.reserve(numKeys);

velox/exec/HashBuild.h

@@ -29,7 +29,7 @@ namespace facebook::velox::exec {
 // Builds a hash table for use in HashProbe. This is the final
 // Operator in a build side Driver. The build side pipeline has
 // multiple Drivers, each with its own HashBuild. The build finishes
-// when the last Driver of the build pipeline finishes. Hence finish()
+// when the last Driver of the build pipeline finishes. Hence finishHashBuild()
 // has a barrier where the last one to enter gathers the data
 // accumulated by the other Drivers and makes the join hash
 // table. This table is then passed to the probe side pipeline via