Exclude bionic private headers from include path

Change-Id: I8b1269a739a690af91c63fa0f7f8f01d2d43bb97
diff --git a/libutils/Threads.cpp b/libutils/Threads.cpp
index cc7fe89..b09d510 100644
--- a/libutils/Threads.cpp
+++ b/libutils/Threads.cpp
@@ -29,7 +29,7 @@
 # include <sched.h>
 # include <sys/resource.h>
 #ifdef HAVE_ANDROID_OS
-# include <bionic_pthread.h>
+# include <private/bionic_pthread.h>
 #endif
 #elif defined(HAVE_WIN32_THREADS)
 # include <windows.h>