Add the necessary machinery into the Meson definition files so that we
can build for Windows.
Since we don't have Wayland or X support for our use case here, disable
them once we know that we are building for Windows, as they are
(otherwise) enabled by default, and enable the items that need to be
built for Windows builds.
Exclude gtk4-launch from Windows builds as that is something that
is not supported on Windows.
As we won't have gio-unix on Windows, and PangoFT2 is optional, don't use
fallbacks for them when we are on Windows (but do use fallbacks for
gio-win32, as it will be used).
Also, clean up meson.build a bit as we can just force-include
msvc_recommended_pragmas.h from GLib since we depend on GLib, and so we
can handle these warnings from msvc_recommended_pragmas.h instead.
https://bugzilla.gnome.org/show_bug.cgi?id=785210
We have to work around some ordering problems here. We still
manage to keep most of the guts in modules/input/meson.build,
so it's not too ugly overall.
(The autotools build solves this with a 'make -C ../../input/modules'
inside gtk/Makefile, but that's not something we can or want to do.)
Add back dependencies on libgdk_dep and libsk_dep which are declared
dependencies. We removed this before because these declarations had
link_with: lines that dragged in the static libgdk.a and libgsk.a libs
which are linked into libgtk-4.so anyway and thus shouldn't be used
when linking internal exes/tools against libgtk-4. Remove the static
libs from the declared dependencies and have libgtk link those in
explicitly, so that the declared deps now just provide all the built
dependencies and include dirs and such for declared libgtk_dep users
such as the internal exes/tools, which want all the generated gsk/gdk/gtk
headers to exist before attempting to compile anything against the
gtk+ headers.
gdkprivate-wayland.h includes generated wayland client protocol
headers and is included from gdkdisplaymanager.c, so we need to
generate those client protocol headers first also when building
main gdk itself.
This is how it's done in the autotools build. Also avoids problems
with multiple source files having the same name (gdkeventsource.c).
Also move broadway backend code into broadway subdir.
