Move timidity, generaluser-gs and openttd-openmsx to GitLab

recipes/generaluser-gs/recipe.sh

 VERSION=1.471
-GIT=https://github.com/xTibor/redox-generaluser-gs.git
+GIT=https://gitlab.redox-os.org/redox-os/generaluser-gs.git
 
 function recipe_version {
     echo "$VERSION"

recipes/openttd-openmsx/recipe.sh

-GIT=https://github.com/xTibor/openttd-openmsx.git
+GIT=https://gitlab.redox-os.org/redox-os/openttd-openmsx.git
 
 function recipe_version {
     echo "0.3.1"

recipes/timidity/recipe.sh

 VERSION=2.14.0
-GIT=https://github.com/xTibor/redox-timidity.git
+GIT=https://gitlab.redox-os.org/redox-os/timidity.git
 BRANCH=redox
 DEPENDS="generaluser-gs"