system/core: Cleanup direct calls to opendir by containing in a
std::unique_ptr.

Bug: 26643633
Change-Id: Ia3491fdbff086558da694ae949cf08e4c89d0307
diff --git a/init/devices.cpp b/init/devices.cpp
index 39cd706..557a6ac 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -31,6 +31,8 @@
 #include <sys/un.h>
 #include <linux/netlink.h>
 
+#include <memory>
+
 #include <selinux/selinux.h>
 #include <selinux/label.h>
 #include <selinux/android.h>
@@ -957,10 +959,9 @@
 
 static void coldboot(const char *path)
 {
-    DIR *d = opendir(path);
+    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path), closedir);
     if(d) {
-        do_coldboot(d);
-        closedir(d);
+        do_coldboot(d.get());
     }
 }