Server launcher: Print errors running java -version to stderr

We forward errors from the spawned server to stderr, so we are
already using stderr and this should save someone some pain
vs. just swallowing the fail.

launch/src/main/scala/xsbt/boot/ServerApplication.scala

@@ -225,7 +225,9 @@ object ServerLauncher {
       val re = """java version "[0-9]+\.([0-9]+)\..*".*""".r
       lineOption flatMap {
         case re(v) => try Some(Integer.parseInt(v) > version) catch { case NonFatal(_) => None }
-        case other => None
+        case other =>
+          System.err.println(s"Failed to parse version from 'java -version' output '$other'")
+          None
       }
     } finally {
       process.destroy()
@@ -235,6 +237,7 @@ object ServerLauncher {
     case e: IOException =>
       // both process.start and reading the output streams can throw IOException.
       // all OS exceptions from process.start are supposed to be IOException.
+      System.err.println(s"Failed to run 'java -version': ${e.getClass.getName}: ${e.getMessage}")
       None
   }