[mygui] Support dynamic linking for MyGUI

[AnyOldName3]

The new patch was accepted upstream as MyGUI/mygui#270, but as other lines have changed in one of the affected files, we need a bespoke patch to work with the 3.4.3 release.

Intended to supersede #41800 as that PR isn't useful without the other changes this one makes.

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[AnyOldName3]

OpenMW's also been carrying 6f1c4b5 in our fork, but that looks like it'd be sensible to upstream, too. Do you want it doing in this PR or a separate one?

[WangWeiLin-MV]

Failed with vcpkg install mygui[*]:x64-windows

BaseManager.cpp.obj : error LNK2019: unresolved external symbol IMG_Init referenced in function "public: virtual bool __cdecl base::BaseManager::createRender(int,int,bool)"

[AnyOldName3]

Failed with vcpkg install mygui[*]:x64-windows

BaseManager.cpp.obj : error LNK2019: unresolved external symbol IMG_Init referenced in function "public: virtual bool __cdecl base::BaseManager::createRender(int,int,bool)"

This should now be resolved - I'd not built with the tools option enabled. The necessary patch is available upstream as MyGUI/mygui#271, but not yet merged when I'm writing this. There's a good chance that it will be by the time you're reading this, though.

[AnyOldName3]

It's now merged upstream, so this PR should work properly, and only contain changes upstream is happy with.

The only remaining question is whether it's preferable to submit 6f1c4b5 as a standalone PR or part of this one.

[WangWeiLin-MV]

The only remaining question is whether it's preferable to submit 6f1c4b5 as a standalone PR or part of this one.

Small PRs follow best practices, I think it's better to separate, https://learn.microsoft.com/en-us/vcpkg/contributing/maintainer-guide#make-separate-pull-requests-per-port.

[WangWeiLin-MV]

The port features installation tests pass with the following triplets:

• x64-linux
• x64-linux-static
• x64-windows
• x64-windows-static