remove emergency shutdown and improve init's reboot logic

- Emergency shutdown just marks the fs as clean while leaving fs
  in the middle of any state. Do not use it anymore.

- Changed android_reboot to set sys.powerctl property so that
  all shutdown can be done by init.

- Normal reboot sequence changed to
    1. Terminate processes (give time to clean up). And wait for
      completion based on ro.build.shutdown_timeout.
        Default value (when not set) is changed to 3 secs. If it is 0, do not
        terminate processes.
    2. Kill all remaining services except critical services for shutdown.
    3. Shutdown vold using "vdc volume shutdown"
    4. umount all emulated partitions. If it fails, just detach.
       Wait in step 5 can handle it.
    5. Try umounting R/W block devices for up to max timeout.
      If it fails, try DETACH.
      If umount fails to complete before reboot, it can be detected when
      system reboots.
    6. Reboot

- Log shutdown time and umount stat to log so that it can be collected after reboot

- To umount emulated partitions, all pending writes inside kernel should
  be completed.
- To umount /data partition, all emulated partitions on top of /data should
  be umounted and all pending writes should be completed.
- umount retry will only wait up to timeout. If there are too many pending
  writes, reboot will discard them and e2fsck after reboot will fix any file system
  issues.

bug: 36004738
bug: 32246772

Test: many reboots combining reboot from UI and adb reboot. Check last_kmsg and
      fs_stat after reboot.

Change-Id: I6e74d6c68a21e76e08cc0438573d1586fd9aaee2
diff --git a/init/reboot.h b/init/reboot.h
new file mode 100644
index 0000000..3956249
--- /dev/null
+++ b/init/reboot.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _INIT_REBOOT_H
+#define _INIT_REBOOT_H
+
+/* Reboot / shutdown the system.
+ * cmd ANDROID_RB_* as defined in android_reboot.h
+ * reason Reason string like "reboot", "userrequested"
+ * rebootTarget Reboot target string like "bootloader". Otherwise, it should be an
+ *              empty string.
+ * runFsck Whether to run fsck after umount is done.
+ */
+void DoReboot(unsigned int cmd, const std::string& reason, const std::string& rebootTarget,
+              bool runFsck) __attribute__((__noreturn__));
+
+#endif