dx: don't check the OS version multiple times

[skyline75489]

Summary of the Pull Request

A tiny little perf fix.

References

PR Checklist

• Closes #xxx
• CLA signed. If not, go over here and sign the CLA
• Tests added/passed
• Requires documentation to be updated
• I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

Detailed Description of the Pull Request / Additional comments

I don't really get it, though. Isn't Windows Terminal only available on Windows 10+?

Validation Steps Performed

[zadjii-msft]

Yea this looks simple enough to me. Thanks!

[zadjii-msft]

I don't really get it, though. Isn't Windows Terminal only available on Windows 10+?

We recently added the WPF version of the TermControl (in #2004). That control isn't used in the Windows Terminal, but does share a lot of code (including the DXRenderer). It's not necessarily bound to the same Windows 10 requirement that the rest of the Terminal is 😄

[DHowett-MSFT]

Yeah, I guess the OS version won't be changing at runtime eh?