Prefer linesIterator to iterate lines

Author: som-snytt

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -667,7 +667,7 @@ trait ParallelTesting extends RunnerOrchestration:
       checkFile(testSource).foreach(diffTest(testSource, _, reporterOutputLines(reporters), reporters, logger))
 
     private def reporterOutputLines(reporters: Seq[TestReporter]): List[String] =
-      reporters.flatMap(_.consoleOutput.split("\n")).toList
+      reporters.flatMap(_.consoleOutput.linesIterator).toList
 
     private[ParallelTesting] def executeTestSuite(): this.type = {
       assert(testSourcesCompleted == 0, "not allowed to re-use a `CompileRun`")