Do not print total bytes written in :core:builtins:serialize

To reduce the amount of output on a clean build. Will have effect after
the next bootstrap update.

compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/builtins/run.kt

@@ -42,6 +42,8 @@ found top-level declarations to <destination dir> (*.kotlin_builtins files)"""
     assert(missing.isEmpty()) { "These source directories are missing: $missing" }
 
     BuiltInsSerializer(dependOnOldBuiltIns = false).serialize(destDir, srcDirs, listOf()) { totalSize, totalFiles ->
-        println("Total bytes written: $totalSize to $totalFiles files")
+        if (System.getProperty("kotlin.builtins.serializer.log") == "true") {
+            println("Total bytes written: $totalSize to $totalFiles files")
+        }
     }
 }

core/builtins/build.gradle.kts

@@ -62,7 +62,10 @@ fun serializeTask(name: String, sourcesTask: TaskProvider<*>, inDirs: List<File>
 
         classpath(rootProject.buildscript.configurations["bootstrapCompilerClasspath"])
         main = "org.jetbrains.kotlin.serialization.builtins.RunKt"
-        jvmArgs("-Didea.io.use.nio2=true")
+        jvmArgs(listOfNotNull(
+            "-Didea.io.use.nio2=true",
+            "-Dkotlin.builtins.serializer.log=true".takeIf { logger.isInfoEnabled }
+        ))
         args(
             pathRelativeToWorkingDir(outDir),
             *inDirs.map(::pathRelativeToWorkingDir).toTypedArray()