Backends: GLFW, SDL: report Windows key (io.KeySuper) as always released.

Neither GLFW nor SDL can correctly report the key release in every cases (e.g. when using Win+V) causing problems with some widgets. The next release of GLFW (3.4+) will have a fix for it. However since it is both difficult and discouraged to make use of this key for Windows application anyway, we just hide it. (#2976)
4 files changed