[SPARK-11191][SQL][FOLLOW-UP] Cleans up unnecessary anonymous HiveFunctionRegistry

According to discussion in PR #9664, the anonymous `HiveFunctionRegistry` in `HiveContext` can be removed now.

Author: Cheng Lian <lian@databricks.com>

Closes #9737 from liancheng/spark-11191.follow-up.

(cherry picked from commit fa13301)
Signed-off-by: Cheng Lian <lian@databricks.com>

Author: liancheng

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala

@@ -412,7 +412,7 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) with Logging {
   // Note that HiveUDFs will be overridden by functions registered in this context.
   @transient
   override protected[sql] lazy val functionRegistry: FunctionRegistry =
-    new HiveFunctionRegistry(FunctionRegistry.builtin, this)
+    new HiveFunctionRegistry(FunctionRegistry.builtin, this.executionHive)
 
   /* An analyzer that uses the Hive metastore. */
   @transient

sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala

@@ -41,16 +41,19 @@ import org.apache.spark.sql.catalyst.expressions.codegen.CodegenFallback
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.hive.HiveShim._
+import org.apache.spark.sql.hive.client.ClientWrapper
 import org.apache.spark.sql.types._
 
 
 private[hive] class HiveFunctionRegistry(
     underlying: analysis.FunctionRegistry,
-    hiveContext: HiveContext)
+    executionHive: ClientWrapper)
   extends analysis.FunctionRegistry with HiveInspectors {
 
   def getFunctionInfo(name: String): FunctionInfo = {
-    hiveContext.executionHive.withHiveState {
+    // Hive Registry need current database to lookup function
+    // TODO: the current database of executionHive should be consistent with metadataHive
+    executionHive.withHiveState {
       FunctionRegistry.getFunctionInfo(name)
     }
   }