[SPARK-20430][SQL] Initialise RangeExec parameters in a driver side

## What changes were proposed in this pull request?
This pr initialised `RangeExec` parameters in a driver side.
In the current master, a query below throws `NullPointerException`;
```
sql("SET spark.sql.codegen.wholeStage=false")
sql("SELECT * FROM range(1)").show

17/04/20 17:11:05 ERROR Executor: Exception in task 0.0 in stage 0.0 (TID 0)
java.lang.NullPointerException
        at org.apache.spark.sql.execution.SparkPlan.sparkContext(SparkPlan.scala:54)
        at org.apache.spark.sql.execution.RangeExec.numSlices(basicPhysicalOperators.scala:343)
        at org.apache.spark.sql.execution.RangeExec$$anonfun$20.apply(basicPhysicalOperators.scala:506)
        at org.apache.spark.sql.execution.RangeExec$$anonfun$20.apply(basicPhysicalOperators.scala:505)
        at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsWithIndex$1$$anonfun$apply$26.apply(RDD.scala:844)
        at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsWithIndex$1$$anonfun$apply$26.apply(RDD.scala:844)
        at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
        at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
        at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
        at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
        at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
        at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
        at org.apache.spark.scheduler.Task.run(Task.scala:108)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:320)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
```

## How was this patch tested?
Added a test in `DataFrameRangeSuite`.

Author: Takeshi Yamamuro <yamamuro@apache.org>

Closes #17717 from maropu/SPARK-20430.

sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala

@@ -331,11 +331,11 @@ case class SampleExec(
 case class RangeExec(range: org.apache.spark.sql.catalyst.plans.logical.Range)
   extends LeafExecNode with CodegenSupport {
 
-  def start: Long = range.start
-  def end: Long = range.end
-  def step: Long = range.step
-  def numSlices: Int = range.numSlices.getOrElse(sparkContext.defaultParallelism)
-  def numElements: BigInt = range.numElements
+  val start: Long = range.start
+  val end: Long = range.end
+  val step: Long = range.step
+  val numSlices: Int = range.numSlices.getOrElse(sparkContext.defaultParallelism)
+  val numElements: BigInt = range.numElements
 
   override val output: Seq[Attribute] = range.output
 

sql/core/src/test/scala/org/apache/spark/sql/DataFrameRangeSuite.scala

@@ -185,6 +185,12 @@ class DataFrameRangeSuite extends QueryTest with SharedSQLContext with Eventuall
       }
     }
   }
+
+  test("SPARK-20430 Initialize Range parameters in a driver side") {
+    withSQLConf(SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key -> "false") {
+      checkAnswer(sql("SELECT * FROM range(3)"), Row(0) :: Row(1) :: Row(2) :: Nil)
+    }
+  }
 }
 
 object DataFrameRangeSuite {