[SPARK-16436][SQL] checkEvaluation should support NaN

## What changes were proposed in this pull request?
This small patch modifies ExpressionEvalHelper. checkEvaluation to support comparing NaN values for floating point comparisons.

## How was this patch tested?
This is a test harness change.

Author: petermaxlee <petermaxlee@gmail.com>

Closes apache#14103 from petermaxlee/SPARK-16436.

Author: petermaxlee

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvalHelper.scala

@@ -63,6 +63,10 @@ trait ExpressionEvalHelper extends GeneratorDrivenPropertyChecks {
         expected.asInstanceOf[Spread[Double]].isWithin(result)
       case (result: MapData, expected: MapData) =>
         result.keyArray() == expected.keyArray() && result.valueArray() == expected.valueArray()
+      case (result: Double, expected: Double) =>
+        if (expected.isNaN) result.isNaN else expected == result
+      case (result: Float, expected: Float) =>
+        if (expected.isNaN) result.isNaN else expected == result
       case _ =>
         result == expected
     }