When cudnn version < 7100, there is problem with conv_fusion.

Add check for it.
test=develop

paddle/fluid/inference/api/demo_ci/vis_demo.cc

@@ -82,10 +82,12 @@ void Main(bool use_gpu) {
 
 int main(int argc, char** argv) {
   google::ParseCommandLineFlags(&argc, &argv, true);
+#if CUDNN_VERSION >= 7100
   if (FLAGS_use_gpu) {
     paddle::demo::Main(true /*use_gpu*/);
   } else {
     paddle::demo::Main(false /*use_gpu*/);
   }
+#endif
   return 0;
 }

paddle/fluid/inference/tests/api/CMakeLists.txt

@@ -144,6 +144,7 @@ if (WITH_ANAKIN AND WITH_MKL) # only needed in CI
     endif()
 endif()
 
+if (NOT ${CUDNN_VERSION} VERSION_LESS 7100)
   if(WITH_GPU AND TENSORRT_FOUND)
     set(TRT_MODEL_INSTALL_DIR "${INFERENCE_DEMO_INSTALL_DIR}/trt")
     if (NOT EXISTS ${TRT_MODEL_INSTALL_DIR})
@@ -153,3 +154,4 @@ if(WITH_GPU AND TENSORRT_FOUND)
             EXTRA_DEPS ${INFERENCE_EXTRA_DEPS}
             ARGS --infer_model=${TRT_MODEL_INSTALL_DIR}/trt_test_models SERIAL)
   endif()
+endif()