Function convBlock

test/expr/ModuleTest.cpp:27–33

When we use MNNConverter to convert other mobilenet model to MNN model, {Conv3x3Depthwise + BN + Relu + Conv1x1 + BN + Relu} will be converted and optimized to {Conv3x3Depthwise + Conv1x1}

// {Conv3x3Depthwise + BN + Relu + Conv1x1 + BN + Relu} will be converted
// and optimized to {Conv3x3Depthwise + Conv1x1}
static VARP convBlock(VARP x, INTS channels, int stride) {
    int inputChannel = channels[0], outputChannel = channels[1];
    int group = inputChannel;
    x         = _Conv(0.01f, 0.0f, x, {inputChannel, inputChannel}, {3, 3}, SAME, {stride, stride}, {1, 1}, group);
    x         = _Conv(0.03f, 0.0f, x, {inputChannel, outputChannel}, {1, 1}, SAME, {1, 1}, {1, 1}, 1);
    return x;
}
static VARP convBlocTemp(VARP x, INTS channels, int stride) {
    int inputChannel = channels[0], outputChannel = channels[1];
    int group = inputChannel;