Move error_code.h into otautil.

This way it stops requiring relative path ".." in LOCAL_C_INCLUDES
(uncrypt and edify). Soong doesn't accept non-local ".." in
"local_include_dirs".

Test: mmma bootable/recovery
Change-Id: Ia4649789cef2aaeb2785483660e9ea5a8b389c62
diff --git a/edify/expr.h b/edify/expr.h
index 4838d20..f2a4d6d 100644
--- a/edify/expr.h
+++ b/edify/expr.h
@@ -23,7 +23,7 @@
 #include <string>
 #include <vector>
 
-#include "error_code.h"
+#include "otautil/error_code.h"
 
 struct State {
     State(const std::string& script, void* cookie);