Fix socket descriptor leak from Zygote to child app

Due to an API change in LocalSocket, Zygote must now
manually close the FileDescriptor it created when it
registered a LocalServerSocket.  The LocalSocket.close()
routine will no longer do so.

Bug: 12114500
Change-Id: I8c9fb073924ac33d594bd3bd0eb11d3d1d402506

core/java/com/android/internal/os/ZygoteInit.java

@@ -192,10 +192,16 @@ public class ZygoteInit {
     static void closeServerSocket() {
         try {
             if (sServerSocket != null) {
+                FileDescriptor fd = sServerSocket.getFileDescriptor();
                 sServerSocket.close();
+                if (fd != null) {
+                    Libcore.os.close(fd);
+                }
             }
         } catch (IOException ex) {
             Log.e(TAG, "Zygote:  error closing sockets", ex);
+        } catch (libcore.io.ErrnoException ex) {
+            Log.e(TAG, "Zygote:  error closing descriptor", ex);
         }
 
         sServerSocket = null;