validate-release: various rewrites

[illwieckz]

• proper shebang
• per-arch linux lib versions
• declare logic more than results (more constraints means more verifications)
• deduplicate Windows checker
• unify some wording
• etc.

[illwieckz]

I have tested this against unvanquished_0.54.0.zip, and linux-amd64.zip and symbols_0.54.0.zip from it.

[illwieckz]

I still kept some bitness code (like if bitness == 32) in Windows checker that can be fully replaced by archness code (like if arch == i686), but I don't know if the given check is for all 32-bit Windows platforms if they exist (arm?) or specific to the x86 32-bit platform. Same for the 64-bit code: would it be the same for arm64 or is it specific to amd64?.

If those checks are truly bitness-specific and not arch-specific, extending the code to set bitness would be doable like that:

- bitness = [32, 64][arch == 'amd64']
+ bitness = [32, 64][arch in ['amd64', 'arm64']]

But we may also just do the if arch === AX where we do if bitness == BX.

[slipher]

Thanks. I merged most of this as 35977d35ffb4ab97880cb58ce595670789681845 with some very minor edits. The major exception is that I'm keeping the hard-coded list of expected symbol files :)

[illwieckz]

everything is merged but things that is now submitted as:

• https://github.com/Unvanquished/validate-release/pull/7