This resulted in -DINCLUDE_IM_ti-et getting passed to gcc resulting in
lots of warnings. Use underscorify() so we get the correct -DINCLUDE_IM_ti_et instead.
We also need to ensure that we pass in -DINCLUDE_IM_xxxx when building
the GTK DLL/.so, in addition to building the respective (static)
immodules, so that we did really link in the immodules into the final
GTK DLL/.so.
Make it a yes/no/auto combo. "yes" means all modules are built into libgtk,
"no" that none are and "auto" uses the platform defaults, yes on win32,
no otherwise.
If we need more we can always extend it later.
Various adjustments to make the config.h output between autotools
and meson more similar by testing on Linux and Windows/MSYS2.
Setting things to 1 instead of true and shifting things around is motivated
by reducing the diff between the generated files.
This changes the configure option into two states:
auto: build all that can be build (default)
A list of backend names: build them and fail if we can't
"papi" is missing because it's not in Debian and I can't test it.
Build the input modules for GTK+, either as modules or built directly
into GTK. Also provide a configure option to build the specified
immodules, or all, or the backend immodule(s) or none of the immodules
into GTK. Note that for Visual Studio all immodules are built into
the GTK DLL by default, like what is done in the Visual Studio projects.
Note that building the backend immodules for Quartz, X11 and Wayland are
currently untested.
This will ensure that the version info is easily visible from the
GDK/GTK+ DLLs, and ensure that the print dialogs will have a more modern
look and feel.
