Fixed x & y coords less than 0

AlexeyAB

2017-03-17 71a9929af6c3d3ffb9527bb921c5cc4a20971ff6

 src/detection_layer.c

@@ -58,7 +58,7 @@
            int index = b*l.inputs;
            for (i = 0; i < locations; ++i) {
                int offset = i*l.classes;
                softmax_array(l.output + index + offset, l.classes, 1,
                softmax(l.output + index + offset, l.classes, 1,
                        l.output + index + offset);
            }
        }