Avoid using sys.env.

Use `System.getenv` instead.

Author: sjrd

js-envs/src/main/scala/org/scalajs/jsenv/ExternalJSEnv.scala

@@ -7,6 +7,7 @@ import org.scalajs.core.tools.jsdep.ResolvedJSDependency
 import java.io.{ Console => _, _ }
 import scala.io.Source
 
+import scala.collection.JavaConverters._
 import scala.concurrent.{Future, Promise}
 import scala.util.Try
 
@@ -67,10 +68,11 @@ abstract class ExternalJSEnv(
 
     /** VM environment. Override to adapt.
      *
-     *  The default value in `ExternalJSEnv` is `sys.env ++ env`.
+     *  The default value in `ExternalJSEnv` is
+     *  `System.getenv().asScala.toMap ++ env`.
      */
     protected def getVMEnv(): Map[String, String] =
-      sys.env ++ env
+      System.getenv().asScala.toMap ++ env
 
     /** Get files that are a library (i.e. that do not run anything) */
     protected def getLibJSFiles(): Seq[VirtualJSFile] =

js-envs/src/main/scala/org/scalajs/jsenv/nodejs/AbstractNodeJSEnv.scala

@@ -19,6 +19,7 @@ import org.scalajs.core.tools.logging.NullLogger
 import org.scalajs.jsenv._
 import org.scalajs.jsenv.Utils.OptDeadline
 
+import scala.collection.JavaConverters._
 import scala.concurrent.TimeoutException
 import scala.concurrent.duration._
 
@@ -139,14 +140,14 @@ abstract class AbstractNodeJSEnv(
 
     // Node.js specific (system) environment
     override protected def getVMEnv(): Map[String, String] = {
-      val baseNodePath = sys.env.get("NODE_PATH").filter(_.nonEmpty)
+      val baseNodePath = Option(System.getenv("NODE_PATH")).filter(_.nonEmpty)
       val nodePath = libCache.cacheDir.getAbsolutePath +
           baseNodePath.fold("")(p => File.pathSeparator + p)
 
-      sys.env ++ Seq(
+      System.getenv().asScala.toMap ++ Seq(
         "NODE_MODULE_CONTEXTS" -> "0",
         "NODE_PATH" -> nodePath
-      ) ++ additionalEnv
+      ) ++ env
     }
   }