Correctly report all Windows x86/x64 OSes in System Information

[PoloniumRain]

The previously submitted PR had build errors with MSVC 2005 and 2010. These have now been fixed. Apart from that, everything else is the same. The previous PR has been copy pasted below to help keep everything in one place.

---

This fixes the incorrect Windows OS being reported in System Information → Frontend OS.

This issue has existed for a very long time, possibly since Windows 8.1, and has been mentioned in #4768, #17712 and #13110, which are now closed. But the problem was never fixed (see latest posts here). The latest stable and nightly builds are still affected.

Windows OSes affected by this issue:

• Windows 11 - All editions
• Windows 10 - All editions
• Windows 8.1 - All editions
• Windows Server 2025, 2022, 2019, 2016, and 2012 R2

Basically, it is all Windows OSes from 8.1 onwards. The problem is partly because of the compiler/manifest.

Here's some examples of OS misreporting with the latest buildbot builds:

OS	RetroArch
Windows 11
Windows 10
Windows 8.1
Windows Server 2025

Changes in this PR:

• Correctly report all Windows OSes from 8.1 onwards. Previously, the deprecated GetVersionEx was used, so OS reporting accuracy depended on manifest compatibility entries that can vary by toolchain and compiler. Windows 8.1+ will intentionally report an older OS when the manifest does not declare support for the OS. This is why Windows 10 shows Windows 8 with buildbot/MinGW 10.2.0 above, but newer MinGW versions will work. RtlGetVersion is now used for OS detection starting from NT 5.0 (Windows 2000), which always reports the actual Windows version regardless of the manifest.
• Report the Windows feature version when available (e.g. 25H2). This is increasingly important given the long lifespan of modern Windows versions (10/11) and how often these feature updates now break/change/add components. Future releases should also be reported correctly without requiring any changes, as the feature version is read from the Windows registry.
• Added detection for Windows Server 2019/2022/2025.
• Correctly report Windows XP Professional x64 Edition and Windows Server 2003/2003 R2/2008/2008 R2. These share the same NT version + build number, which was causing detection to fail.
• Detect Windows 98 Second Edition separately from Windows 98, which is a distinct OS revision with meaningful system and driver differences.
• Change Windows Me being reported as Windows ME to Windows Me (official documentation always uses a lower-case e. So i've been typing it wrong for 25+ years...).
• Improve readability of the reported OS by inserting a -. For example: Windows 11 (25H2) x64 - Build 26200
• Made fallbacks more robust and improved clarity. They will now show either: Windows NT kernel x.x or Windows 9x version x.x. Previously it would show Windows x.x, which could be mistaken for the OS name.
• Added many code comments to help maintainability.

Accurately reporting the Windows OS involves many edge cases and historical inconsistencies, so all Windows versions listed below were tested using x86/x64 builds from many different MSVC and MinGW compiler versions (yeah it took ages!).

OS (by release date)	RetroArch
Windows 11 Insider Preview (latest Dev channel build)	Now reported correctly.
Windows 11 Insider Preview (older Dev channel build)	Note: Windows Insider builds may report channel names (e.g. “Dev”), as this is sometimes stored in the registry, instead of the feature version name.
Windows 11 (25H2)	Now reported correctly.
Windows Server 2025 (24H2)	Newly added.
Windows 11 IoT Enterprise (24H2)	An example of a more obscure Windows edition. Different editions make no difference to OS detection accuracy.
Windows 10 (22H2)	Now reported correctly.
Windows Server 2022 (21H2)	Newly added.
Windows Server 2019 (1809)	Newly added.
Windows Server 2016 (1607)	Now reported correctly.
Windows 10 (1507) (first released version)	Note: Earlier Win10/Server releases used a different feature version format, e.g. 1507 (year/month) instead of the current year/half-year format.
Windows Server 2012 R2	Now reported correctly.
Windows 8.1	Now reported correctly.
Windows 8
Windows Server 2012
Windows 7
Windows Server 2008 R2	Now reported correctly.
Windows Server 2008	Now reported correctly.
Windows Vista
Windows Server 2003 R2	Now reported correctly.
Windows XP x64	Now reported correctly. Note: XP x64 only had a single edition released, making it safe/easy to use the full product name here.
Windows Server 2003	Now reported correctly.
Windows XP
Windows Me	Now displays Me instead of ME.
Windows 2000
Windows 98 Second Edition	Newly added.
Windows 98
Windows 95 and NT 4.0	Were not tested. RA hasn't worked on these OSes for a long time, but they should be reported correctly if builds were made to work on them.