GH-131296: fix clang-cl warnings on Windows in blake2module.c

[chris-eibl]

Fix

1>..\Modules\blake2module.c(77,9): warning : variable 'eax1' set but not used [-Wunused-but-set-variable]
1>..\Modules\blake2module.c(77,19): warning : variable 'ebx1' set but not used [-Wunused-but-set-variable]
1>..\Modules\blake2module.c(78,9): warning : variable 'eax7' set but not used [-Wunused-but-set-variable]
1>..\Modules\blake2module.c(78,29): warning : variable 'ecx7' set but not used [-Wunused-but-set-variable]
1>..\Modules\blake2module.c(78,39): warning : variable 'edx7' set but not used [-Wunused-but-set-variable]

we see them two (non-PGO) or three times, because the _freeze_module compiles blake2module.c, too.

I think this is a skip news.

• Issue: clang-cl issues many warnings when building on Windows #131296

[gpshead]

LOL... definitely fighting against the compiler's idea of best practices here using useless no-op statements as a way to work around it. i wish we could disable a specific warning for a whole block of code. i feel like a future compiler will notice that these are useless and stop considering them a "use".

[chris-eibl]

It was just the least minimal change to silence the warning :)

Luckily, I think we'll never have to fear that this will ever need a change: that (void) pattern is adapted by all known compilers for ages - and I think this will stay.

[picnixz]

Ideally, we would have used (void) ... in the elif branch but it would be an overkill for foolish consistency.

[picnixz]

Can you remove the double blank lines L98/L99 please? TiA

[picnixz]

Oh it was merged :')