[refactor] Use uint64_t and std namespace in PoissonNextSend

Co-authored-by: Martin Zumsande <mzumsande@gmail.com>

src/random.cpp

@@ -718,6 +718,6 @@ void RandomInit()
 
 std::chrono::microseconds PoissonNextSend(std::chrono::microseconds now, std::chrono::seconds average_interval)
 {
-    double unscaled = -log1p(GetRand(1ULL << 48) * -0.0000000000000035527136788 /* -1/2^48 */);
+    double unscaled = -std::log1p(GetRand(uint64_t{1} << 48) * -0.0000000000000035527136788 /* -1/2^48 */);
     return now + std::chrono::duration_cast<std::chrono::microseconds>(unscaled * average_interval + 0.5us);
 }