ui/sdl2: ignore GUI keys in SDL_TEXTINPUT handler

ui/sdl2: ignore GUI keys in SDL_TEXTINPUT handler

Ignore GUI keys for SDL_TEXTINPUT events, just like GUI keys are
ignored for SDL_KEYDOWN events. This prevents unintended text input
in a text console when hiding the text console with the GUI keys.

The SDL_TEXTINPUT event always comes after the SDL_KEYDOWN event.
See https://github.com/libsdl-org/SDL/issues/1659.

Tested-by: Howard Spoelstra <hsp.cat7@gmail.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Tested-by: Bernhard Beschow <shentey@gmail.com>
Message-ID: <20240909061552.6122-3-vr_qemu@t-online.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>