Move bionic_macros.h from private to platform.

Test: treehugger
Change-Id: Ie473914f4c8924c7240b3ac22093a9daf42fc948
diff --git a/libc/bionic/scandir.cpp b/libc/bionic/scandir.cpp
index 0b39049..6a7e368 100644
--- a/libc/bionic/scandir.cpp
+++ b/libc/bionic/scandir.cpp
@@ -22,7 +22,7 @@
 #include <string.h>
 #include <unistd.h>
 
-#include "private/bionic_macros.h"
+#include "platform/bionic/macros.h"
 #include "private/ScopedReaddir.h"
 
 // A smart pointer to the scandir dirent**.