cpuminer-opt-3.21.4

Windows GBT crashes have been reported with this release as well.
The root cause has been found and a new release is forthcoming.

Reapply selected changes from v3.21.3.
#392 #379 #389 Fixed misaligned address segfault solo mining.
#392 Fixed conditional mining.
#392 Fixed cpu affinity on Ryzen CPUs using Windows binaries,
Windows binaries no longer support CPU groups,
Windows binaries support CPUs with up to 64 threads.