This assumption breaks when, for instance:
* Called as /bin/gdbus-codegen
* Installed on Windows in a directory that is not `bin/`
For such cases, we cannot make any assumptions about the directory
structure, and must hard-code the datadir.
https://bugzilla.gnome.org/show_bug.cgi?id=786785
Disable gio tests on Windows, fix .gitignore to not ignore
config.h.meson, and add more things to it.
Rename the library file naming and versioning to match what Autotools
outputs, e.g., libglib-2.0.so.0.5000.2 on Linux, libglib-2.0-0.dll and
glib-2.0-0.dll on Windows with MSVC.
Several more tiny fixes, more executables built and installed, install
pkg-config and m4 files, fix building of gobject tests.
Changes to gdbus-codegen to support out-of-tree builds without
environment variables set (which you can't in Meson). We now add the
build directory to the Python module search path.
