[SPARK-5999][SQL] Remove duplicate Literal matching block

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #4760 from viirya/dup_literal and squashes the following commits:

06e7516 [Liang-Chi Hsieh] Remove duplicate Literal matching block.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala

@@ -38,6 +38,8 @@ object Literal {
     case d: Date => Literal(DateUtils.fromJavaDate(d), DateType)
     case a: Array[Byte] => Literal(a, BinaryType)
     case null => Literal(null, NullType)
+    case _ =>
+      throw new RuntimeException("Unsupported literal type " + v.getClass + " " + v)
   }
 }
 

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -74,25 +74,7 @@ object functions {
       case _ =>  // continue
     }
 
-    val literalExpr = literal match {
-      case v: Boolean => Literal(v, BooleanType)
-      case v: Byte => Literal(v, ByteType)
-      case v: Short => Literal(v, ShortType)
-      case v: Int => Literal(v, IntegerType)
-      case v: Long => Literal(v, LongType)
-      case v: Float => Literal(v, FloatType)
-      case v: Double => Literal(v, DoubleType)
-      case v: String => Literal(v, StringType)
-      case v: BigDecimal => Literal(Decimal(v), DecimalType.Unlimited)
-      case v: java.math.BigDecimal => Literal(Decimal(v), DecimalType.Unlimited)
-      case v: Decimal => Literal(v, DecimalType.Unlimited)
-      case v: java.sql.Timestamp => Literal(v, TimestampType)
-      case v: java.sql.Date => Literal(v, DateType)
-      case v: Array[Byte] => Literal(v, BinaryType)
-      case null => Literal(null, NullType)
-      case _ =>
-        throw new RuntimeException("Unsupported literal type " + literal.getClass + " " + literal)
-    }
+    val literalExpr = Literal(literal)
     Column(literalExpr)
   }