chore: import upstream snapshot with attribution

tools/train/source/parameters/Distributions.cpp

@@ -0,0 +1,30 @@
+//
+//  Distributions.cpp
+//  MNN
+//
+//  Created by MNN on 2019/11/28.
+//  Copyright © 2018, Alibaba Group Holding Limited
+//
+
+#include "Distributions.hpp"
+#include <cmath>
+
+namespace MNN {
+namespace Train {
+
+void Distributions::uniform(const int count, const float min, const float max, float *r, std::mt19937 gen) {
+    std::uniform_real_distribution<float> dis(min, std::nextafter(max, std::numeric_limits<float>::max()));
+    for (int i = 0; i < count; i++) {
+        r[i] = dis(gen);
+    }
+}
+
+void Distributions::gaussian(const int count, const float mu, const float sigma, float *r, std::mt19937 gen) {
+    std::normal_distribution<float> dis(mu, sigma);
+    for (int i = 0; i < count; i++) {
+        r[i] = dis(gen);
+    }
+}
+
+} // namespace Train
+} // namespace MNN