add gemm merge function C = A * B +bias

src/operators/math/math_function.h

@@ -24,7 +24,8 @@ namespace math {
 template <typename T>
 void matmul(const framework::Tensor &matrix_a, bool trans_a,
             const framework::Tensor &matrix_b, bool trans_b, T alpha,
-            framework::Tensor *matrix_out, T beta, bool relu = false, float *bias = nullptr);
+            framework::Tensor *matrix_out, T beta, bool relu = false,
+            float *bias = nullptr);
 
 template <typename T>
 void matmulWithBn(const framework::Tensor &matrix_a, bool trans_a,