Revert "glx: Lift sending the MakeCurrent request to top-level code"

This provokes crashes in Cinnamon for some reason that I haven't diagnosed yet.

This reverts commit 80b67a3b.

Fixes: #4639 (closed)

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@eric once I'm sure this passes CI (I don't trust anything anymore) I'll make a corresponding revert for the 21.1 branch.