Move std.c to arch to avoid conflicts with libc for tests.

Change-Id: I0fc966962413ee12f84058d702e7396e38460f27
diff --git a/inc/hf/std.h b/inc/hf/arch/std.h
similarity index 98%
rename from inc/hf/std.h
rename to inc/hf/arch/std.h
index 6609978..c8a03a5 100644
--- a/inc/hf/std.h
+++ b/inc/hf/arch/std.h
@@ -64,6 +64,7 @@
 #define align_down(v, a) ((uintptr_t)(v) & ~(a - 1))
 #endif
 
+#ifndef be16toh
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 
 #define be16toh(v) __builtin_bswap16(v)
@@ -110,3 +111,4 @@
 #error "Unsupported byte order"
 
 #endif
+#endif