MKLDNN conv + elementwise_add fusion: turn on residual connection pass when CAPI is used.

test=develop

paddle/fluid/inference/analysis/analyzer.h

@@ -81,6 +81,7 @@ class Analyzer : public OrderedRegistry<PassManager> {
 #ifdef PADDLE_WITH_MKLDNN
       "conv_bias_mkldnn_fuse_pass",  //
       "conv_relu_mkldnn_fuse_pass",             //
+      "conv_elementwise_add_mkldnn_fuse_pass",  //
 #endif
   }};