Basic memory sharing.

The introduces the basic functionality for memory sharing. The API used
to invoke memory sharing is a placeholder while we decide on what the
proper interface should look like.

Change-Id: Ia5c2c224119d896b3fc2294b0828626ec325e1e7
diff --git a/inc/hf/std.h b/inc/hf/std.h
index c872fd4..6e5e82a 100644
--- a/inc/hf/std.h
+++ b/inc/hf/std.h
@@ -19,6 +19,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+
 void *memset(void *s, int c, size_t n);
 void *memcpy(void *dst, const void *src, size_t n);
 void *memmove(void *dst, const void *src, size_t n);