only do test_ConvUnify when there is a gpu

paddle/gserver/tests/test_ConvUnify.cpp

@@ -94,6 +94,7 @@ MatrixPtr doOneConvTest(size_t imgSize, size_t output_x, size_t stride,
 }
 
 TEST(Layer, convParaUnified) {
+  #ifndef PADDLE_ONLY_CPU
     MatrixPtr input, resultCpu, resultGpu;
     input = Matrix::create(1, 4 * 4, false, false);
     float inputData[] = {1, 2, 3, 4,
@@ -155,6 +156,7 @@ TEST(Layer, convParaUnified) {
                        /*numfilters*/ 2,
                        input, param2, true);
     checkMatrixEqual(resultCpu, resultGpu);
+  #endif
 }
 
 int main(int argc, char** argv) {