Move bionic_macros.h from private to platform.

Test: treehugger
Change-Id: Ie473914f4c8924c7240b3ac22093a9daf42fc948
diff --git a/libc/bionic/mremap.cpp b/libc/bionic/mremap.cpp
index a4e5323..d7c9353 100644
--- a/libc/bionic/mremap.cpp
+++ b/libc/bionic/mremap.cpp
@@ -32,7 +32,7 @@
 #include <stdint.h>
 #include <unistd.h>
 
-#include "private/bionic_macros.h"
+#include "platform/bionic/macros.h"
 
 extern "C" void* __mremap(void*, size_t, size_t, int, void*);