Move bionic_macros.h from private to platform.

Test: treehugger
Change-Id: Ie473914f4c8924c7240b3ac22093a9daf42fc948
diff --git a/libc/private/ScopedFd.h b/libc/private/ScopedFd.h
index 1cec916..ea7f59e 100644
--- a/libc/private/ScopedFd.h
+++ b/libc/private/ScopedFd.h
@@ -30,7 +30,7 @@
 
 #include <unistd.h>
 
-#include "private/bionic_macros.h"
+#include "platform/bionic/macros.h"
 #include "private/ErrnoRestorer.h"
 
 class ScopedFd final {