init: Allow clean system shutdown upon SIGTERM

This allows Android to cleanly shutdown when running in a PID namespace
in a way that does not rely on adbd running. This is useful to allow
Android to be running in a container and its lifetime managed by an
OCI-compliant tool.

Bug: 65415372
Test: `kill -TERM 1` as root is correctly dropped.
Test: `kill -TERM 1` from the init PID namespace causes init to cleanly shutdown.
Change-Id: Ia66ebdb436221919081bc4723337c0c7f1e53b09
diff --git a/init/Android.bp b/init/Android.bp
index 8737def..672942e 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -119,7 +119,7 @@
         "init_first_stage.cpp",
         "keychords.cpp",
         "reboot.cpp",
-        "signal_handler.cpp",
+        "sigchld_handler.cpp",
         "ueventd.cpp",
         "watchdogd.cpp",
     ],