Fix missing errno.h includes after libc cleanup.

These issues hadn't been found yet because a libc++ header was
unconditionally pulling in errno.h. I've fixed the libc++ header now.

Change-Id: Ib096634cdd231fc75bf7548e4b99babc7442dc53
diff --git a/server/InterfaceController.cpp b/server/InterfaceController.cpp
index 061060f..14f0da7 100644
--- a/server/InterfaceController.cpp
+++ b/server/InterfaceController.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <dirent.h>
+#include <errno.h>
 
 #define LOG_TAG "InterfaceController"
 #include <cutils/log.h>