randomSeed: Bad/redundant "if"

Hi,

In function `randomSeed` (`WMath.cpp`, line 30) there's the code

```cpp
if (seed != 0) {
srandom(seed);
}
```

Since "srandom" handles the value 0 itself (see for example its implementation in `random.c` of AVR-Libc*), it seems there's no need for that "if". Furthermore, it is undocumented and may break functionality - for instance, if a user wants to produce two identical pseudo-random sequences using the seed 0.
- https://github.com/vancegroup-mirrors/avr-libc/blob/master/avr-libc/libc/stdlib/random.c

If that "if" can be removed, it will save a byte or two.

See discussion about this here (not all of it directly relevant): https://forum.arduino.cc/t/randomseed-why-is-0-ignored/337424

Thanks,