[SPARK-25863][SPARK-21871][SQL] Check if code size statistics is empty or not in updateAndGetCompilationStats

## What changes were proposed in this pull request?
`CodeGenerator.updateAndGetCompilationStats` throws an unsupported exception for empty code size statistics. This pr added code to check if it is empty or not.

## How was this patch tested?
Pass Jenkins.

Closes #23947 from maropu/SPARK-21871-FOLLOWUP.

Authored-by: Takeshi Yamamuro <yamamuro@apache.org>
Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>

Author: maropu

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala

@@ -1472,7 +1472,11 @@ object CodeGenerator extends Logging {
       }
     }.flatten
 
-    codeSizes.max
+    if (codeSizes.nonEmpty) {
+      codeSizes.max
+    } else {
+      0
+    }
   }
 
   /**