Problem: Crash when using garbagecollect() in between rand().
Solution: Redesign the rand() and srand() implementation. (Yasuhiro
Matsumoto, closesvim/vim#5587, closesvim/vim#5588)
4f645c54ef
Omit test_srand_seed.
Unmacroify SHUFFLE_XOSHIRO128STARSTAR and SPLITMIX32 while we're at it (leave
ROTL alone as it's fairly innocent).