fix compile warning in test_MKLDNN.cpp and ROIPoolLayer.cpp

Author: luotao1

paddle/gserver/layers/ROIPoolLayer.cpp

@@ -98,7 +98,7 @@ void ROIPoolLayer::forward(PassType passType) {
     size_t roiStartH = round(bottomROIs[2] * spatialScale_);
     size_t roiEndW = round(bottomROIs[3] * spatialScale_);
     size_t roiEndH = round(bottomROIs[4] * spatialScale_);
-    CHECK_GE(roiBatchIdx, 0);
+    CHECK_GE(roiBatchIdx, 0UL);
     CHECK_LT(roiBatchIdx, batchSize);
     size_t roiHeight = std::max(roiEndH - roiStartH + 1, 1UL);
     size_t roiWidth = std::max(roiEndW - roiStartW + 1, 1UL);

paddle/gserver/tests/test_MKLDNN.cpp

@@ -297,7 +297,7 @@ static void getAddtoConfig(TestConfig& cfg,
 }
 
 void testAddtoLayer(const testImageDesc& pm, const size_t nInputs) {
-  CHECK_GE(nInputs, 1);
+  CHECK_GE(nInputs, 1UL);
   TestConfig dnnConfig;
   getAddtoConfig(dnnConfig, pm, nInputs);
   dnnConfig.layerConfig.set_type("mkldnn_addto");