Move bionic_macros.h from private to platform.

Test: treehugger
Change-Id: Ie473914f4c8924c7240b3ac22093a9daf42fc948
diff --git a/libc/private/ScopedSignalBlocker.h b/libc/private/ScopedSignalBlocker.h
index 10aacb3..ce0ae64 100644
--- a/libc/private/ScopedSignalBlocker.h
+++ b/libc/private/ScopedSignalBlocker.h
@@ -18,7 +18,7 @@
 
 #include <signal.h>
 
-#include "bionic_macros.h"
+#include "platform/bionic/macros.h"
 
 class ScopedSignalBlocker {
  public: