Move watchdogd out of init

We're moving past a world where static executables are needed,
including watchdogd, so treat this like any other executable and place
it in /system/bin.

Bug: 73660730
Test: watchdogd still runs
Change-Id: I1f7508fd55dce6e9ee72a6ab7a085011a76c0053
diff --git a/init/selinux.h b/init/selinux.h
index 30069b5..c41d7f0 100644
--- a/init/selinux.h
+++ b/init/selinux.h
@@ -27,7 +27,7 @@
 void SelinuxRestoreContext();
 
 void SelinuxSetupKernelLogging();
-bool SelinuxHasVendorInit();
+int SelinuxGetVendorAndroidVersion();
 
 void SelabelInitialize();
 bool SelabelLookupFileContext(const std::string& key, int type, std::string* result);