Move bionic_macros.h from private to platform.

Test: treehugger
Change-Id: Ie473914f4c8924c7240b3ac22093a9daf42fc948
diff --git a/libc/private/KernelArgumentBlock.h b/libc/private/KernelArgumentBlock.h
index c8ce841..ee28d69 100644
--- a/libc/private/KernelArgumentBlock.h
+++ b/libc/private/KernelArgumentBlock.h
@@ -21,7 +21,7 @@
 #include <stdint.h>
 #include <sys/auxv.h>
 
-#include "private/bionic_macros.h"
+#include "platform/bionic/macros.h"
 
 // When the kernel starts the dynamic linker, it passes a pointer to a block
 // of memory containing argc, the argv array, the environment variable array,