Brunel HH Example behaves differently with Apple Clang.

[thorstenhater]

As seen during #2430
the HH-Brunel network example exhibits a (small) divergence in spike counts
when compiled with Apple Clang. A potential explanation might be this observation

https://stackoverflow.com/questions/76407947/trivial-c-program-yields-different-result-in-clang-macos-arm64-and-clang-macos-x

but we need some more investigation.

[thorstenhater]

So, some investigation notes:

• HH produces a bitwise-identical voltage trace across Clang, AClang, GCC
• This remains true regardless of stimulus (IClamp, Poisson input)
• However, the Brunel network is not identical

This is due to std::uniform_int_distribution not being portable across compilers (also not demanded by ISO C++), but fortunately MT is portable (thus inputs are identical, but ints drawn from the generator are not)