Since we use XCB in the Mutter side, but Xlib in the frames client,
we cannot share the same struct definition since both libraries
will expect different type lengths (respectively, 32-bit ints vs.
longs).
Revert the changes that made both executables share the same
struct, since not both of them can get it right (and retrieve
correctly the struct with the contained flags) in reading the
Motif WM hints.
This reverts commit 2fb3c5a4f577aea9a4fc721807eb1ca4a49b8990.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2741>
66b1f43967