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/signal_handler.cpp b/init/signal_handler.cpp
index 183837b..db1bfcf 100644
--- a/init/signal_handler.cpp
+++ b/init/signal_handler.cpp
@@ -25,6 +25,9 @@
 #include "init.h"
 #include "service.h"
 
+namespace android {
+namespace init {
+
 static int signal_write_fd = -1;
 static int signal_read_fd = -1;
 
@@ -64,3 +67,6 @@
 
     register_epoll_handler(signal_read_fd, handle_signal);
 }
+
+}  // namespace init
+}  // namespace android