Update sdlthread.inc to version 2.26.2

[Free-Pascal-meets-SDL-Website]

• Updates sdlthread.inc to version 2.26.2 (for the most part)
• OS/2-block left out (was not translated beforehand)
• Some Todos are left (see comments in code for reference); to my mind they are not of high importance (see TpfnSDL_CurrentBeginThread, TThreadID); nobody ever complained about these structures => raises the question, if anybody uses SDL threads in Pascal anyway, since Pascal provides high quality procedural and object-oriented thread management

[suve]

@Free-Pascal-meets-SDL-Website Can you sync this PR with the latest master branch and also check if SDL 2.28 or SDL 2.30 added anything?

[Free-Pascal-meets-SDL-Website]

@Free-Pascal-meets-SDL-Website Can you sync this PR with the latest master branch and also check if SDL 2.28 or SDL 2.30 added anything?

I sync'd it. No new functions got introduced.

[suve]

Looks ok, though my comment regarding the dynamic API stuff for Windows still stands. I can take care of that in a follow-up PR, if you'd like.

[Free-Pascal-meets-SDL-Website]

Looks ok, though my comment regarding the dynamic API stuff for Windows still stands. I can take care of that in a follow-up PR, if you'd like.

Sure, would be great.