Port MetaRectangle to Mutter API version 13
In GNOME 45's development cycle, MetaRectangle gets refactored and named to MtkRectangle. So, replace the former with the latter.
See: mutter!3128 (merged)
In GNOME 45's development cycle, MetaRectangle gets refactored and named to MtkRectangle. So, replace the former with the latter.
See: mutter!3128 (merged)