NativeCrashListener: fix file descriptor leak.

Sending thousands of crashes can result in the system
eventually running out of file descriptors. Close file
descriptors after we're done with them.

Change-Id: I09ae9ce36426ded3fd591dda9a3550a19c2f01d3
diff --git a/services/java/com/android/server/am/NativeCrashListener.java b/services/java/com/android/server/am/NativeCrashListener.java
index 307ab03..2c7f1f1 100644
--- a/services/java/com/android/server/am/NativeCrashListener.java
+++ b/services/java/com/android/server/am/NativeCrashListener.java
@@ -152,6 +152,13 @@
                                 Slog.d(TAG, "Exception writing ack: " + e.getMessage());
                             }
                         }
+                        try {
+                            Libcore.os.close(peerFd);
+                        } catch (ErrnoException e) {
+                            if (MORE_DEBUG) {
+                                Slog.d(TAG, "Exception closing socket: " + e.getMessage());
+                            }
+                        }
                     }
                 }
             }