Update rng.hpp #741

Job	Run time
msvc-x64, Release, Shared=ON	5m 38s
msvc-x64, Release, Shared=OFF	5m 47s
clang-x64, Release, Shared=ON	8m 18s
clang-x64, Release, Shared=OFF	9m 34s
msvc-x64, RelWithDebInfo, Shared=ON	6m 25s
msvc-x64, RelWithDebInfo, Shared=OFF	5m 16s
clang-x64, RelWithDebInfo, Shared=ON	8m 15s
clang-x64, RelWithDebInfo, Shared=OFF	8m 10s
msvc-Win32, RelWithDebInfo, Shared=ON	5m 27s
msvc-Win32, RelWithDebInfo, Shared=OFF	5m 32s
clang-Win32, RelWithDebInfo, Shared=ON	10m 4s
clang-Win32, RelWithDebInfo, Shared=OFF	10m 32s
	1h 28m 58s

Provide feedback