init: create android::init:: namespace

With some small fixups along the way

Test: Boot bullhead
Test: init unit tests
Change-Id: I7beaa473cfa9397f845f810557d1631b4a462d6a
diff --git a/init/reboot.cpp b/init/reboot.cpp
index cdfc698..df7912f 100644
--- a/init/reboot.cpp
+++ b/init/reboot.cpp
@@ -53,6 +53,9 @@
 
 using android::base::StringPrintf;
 
+namespace android {
+namespace init {
+
 // represents umount status during reboot / shutdown.
 enum UmountStat {
     /* umount succeeded. */
@@ -468,3 +471,6 @@
     DoReboot(cmd, command, reboot_target, run_fsck);
     return true;
 }
+
+}  // namespace init
+}  // namespace android