Currently, we dispatch the events on the wayland display server ourselves.
This is fine when using the cairo backend of libdecor, as it does the same
thign we do, but other backends may require other things to be dispatched.
This commit lets libdecor dispatch events instead through libdecor_get_fd
and libdecor_dispatch, which should hopefully makes things less sketchy.
This commit fixes the -Wmissing-field-initializers warning, which can only
be disabled with a pragma. GCC wants us to Initialize libdecor reserved
fields, which requires knowing how many reserved fields there are.
This is an implementation detail, and so we can only disable the warning.
This also fixes -Wincompatible-pointer-types, which is an actual bug.
