[K/N] Reduce frame size by removing unused arena field.

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/cexport/CAdapterApiExporter.kt

@@ -289,7 +289,6 @@ internal class CAdapterApiExporter(
     |}  // extern "C"
     |
     |struct ${prefix}_FrameOverlay {
-    |  void* arena;
     |  ${prefix}_FrameOverlay* previous;
     |  ${prefix}_KInt parameters;
     |  ${prefix}_KInt count;
@@ -406,4 +405,4 @@ private operator fun String.times(count: Int): String {
 }
 
 private val KotlinType.shortNameForPredefinedType
-    get() = this.toString().split('.').last()
+    get() = this.toString().split('.').last()