Revert "libbinder: Replace deprecated utils/threads.h header"

This reverts commit bc8d5b4830d7fb5afe52f9d8809212babedd72b1.

Reason for revert: breaks libvrflinger build

Change-Id: I767dbf3ed56893ead497184d2204a04156faaa9d
diff --git a/libs/binder/MemoryDealer.cpp b/libs/binder/MemoryDealer.cpp
index 03553f3..c4475c7 100644
--- a/libs/binder/MemoryDealer.cpp
+++ b/libs/binder/MemoryDealer.cpp
@@ -23,6 +23,7 @@
 #include <utils/Log.h>
 #include <utils/SortedVector.h>
 #include <utils/String8.h>
+#include <utils/threads.h>
 
 #include <stdint.h>
 #include <stdio.h>