Refactor the process of choosing validators.

src/trusted/service_runtime/sel_ldr.h

Index: src/trusted/service_runtime/sel_ldr.h
diff --git a/src/trusted/service_runtime/sel_ldr.h b/src/trusted/service_runtime/sel_ldr.h
index 4509c905aacadf25318f18321a310e6f938fdfe4..e3dc1fdc2dfc91fbb5640fc2150196d3e2580b8c 100644
--- a/src/trusted/service_runtime/sel_ldr.h
+++ b/src/trusted/service_runtime/sel_ldr.h
@@ -53,6 +53,7 @@
 #include "native_client/src/trusted/service_runtime/name_service/name_service.h"
 
 #include "native_client/src/trusted/validator/cpufeatures.h"
+#include "native_client/src/trusted/validator/ncvalidate.h"
 
 EXTERN_C_BEGIN
 
@@ -365,7 +366,7 @@ struct NaClApp {
   enum NaClDebugExceptionHandlerState debug_exception_handler_state;
   NaClAttachDebugExceptionHandlerFunc attach_debug_exception_handler_func;
 #endif
-  int                       enable_dfa_validator;
+  const struct NaClValidatorInterface *validator;
 };