[clang] [ARM][AArch64] Add missing Neon Types (PR #126945)

[David Green via cfe-commits]

https://github.com/davemgreen commented:

Hi - I tried this with the latest https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/config/cpu/aarch64/opt/ext/opt_random.h and it seemed to need some fixes and then it might have failed to mangle the types if they were used? I can provide a reproducer if that would be helpful, it looked like it nearly worked, it worked until I added the rng() call.

(It is essentially a file like this, on aarch64, on a machine with ext/opt_random.h from the link above, compiled with `clang++ -S -o - random.cpp -I. -O3`)
```
#include <random>
#include <ext/random>

int main(int argc, char** argv) {
  __gnu_cxx::sfmt19937 rng;
  return rng();
}
```

https://github.com/llvm/llvm-project/pull/126945