gitignore: remove deprecated ts_test_mt_sdl entry
gitignore: remove deprecated ts_test_mt_sdl entry

We keep the name ts_test_mt when configured --with-sdl2

Signed-off-by: Martin Kepplinger <07ddf30bcca2a0d3056e54ffbfe155352a6af244@posteo.de>

kergoth/tslib,kergoth/tslib,kergoth/tslib,kergoth/tslib