stylable: avoid using g_strdup_printf where g_strconcat is acceptable
stylable: avoid using g_strdup_printf where g_strconcat is acceptable

Avoid the additional overhead of using printf when the string can be
constructed by simply concatenating strings together.

clutter-project/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx