Merge pull request scala#5365 from szeiger/wip/junit-stack-size

Decrease stack size for JUnit tests to 1M (same as the old ant build)

Author: szeiger

build.sbt

@@ -556,7 +556,7 @@ lazy val junit = project.in(file("test") / "junit")
   .settings(disablePublishing: _*)
   .settings(
     fork in Test := true,
-    javaOptions in Test += "-Xss5M",
+    javaOptions in Test += "-Xss1M",
     libraryDependencies ++= Seq(junitDep, junitInterfaceDep, jolDep),
     testOptions += Tests.Argument(TestFrameworks.JUnit, "-a", "-v"),
     testFrameworks -= new TestFramework("org.scalacheck.ScalaCheckFramework"),