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

Change-Id: I0fc966962413ee12f84058d702e7396e38460f27
diff --git a/src/vm.c b/src/vm.c
index b68c219..a597e3f 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -16,9 +16,10 @@
 
 #include "hf/vm.h"
 
+#include "hf/arch/std.h"
+
 #include "hf/api.h"
 #include "hf/cpu.h"
-#include "hf/std.h"
 
 #include "vmapi/hf/call.h"