Make "bazel info server_pid" work on Windows.

This is the first actual use of Windows JNI!

Also a cleanup of ProcessUtils. Injecting a mock implementation was never used.

--
MOS_MIGRATED_REVID=126068832
diff --git a/src/main/java/com/google/devtools/build/lib/shell/Consumers.java b/src/main/java/com/google/devtools/build/lib/shell/Consumers.java
index 37df646..972bfa8 100644
--- a/src/main/java/com/google/devtools/build/lib/shell/Consumers.java
+++ b/src/main/java/com/google/devtools/build/lib/shell/Consumers.java
@@ -129,8 +129,7 @@
   /**
    * This consumer sends the input to a stream while consuming it.
    */
-  private static class StreamingConsumer extends FutureConsumption
-                                         implements OutputConsumer {
+  private static class StreamingConsumer extends FutureConsumption {
     private OutputStream out;
 
     StreamingConsumer(OutputStream out) {
@@ -158,8 +157,7 @@
    * while consuming it. This accumulated stream can be obtained by
    * calling {@link #getAccumulatedOut()}.
    */
-  private static class AccumulatingConsumer extends FutureConsumption
-                                            implements OutputConsumer {
+  private static class AccumulatingConsumer extends FutureConsumption {
     private ByteArrayOutputStream out = new ByteArrayOutputStream();
 
     @Override
@@ -180,8 +178,7 @@
   /**
    * This consumer just discards whatever it reads.
    */
-  private static class DiscardingConsumer extends FutureConsumption
-                                          implements OutputConsumer {
+  private static class DiscardingConsumer extends FutureConsumption {
     private DiscardingConsumer() {
     }