The demos are now built as GUI programs, which will require the presence
of WinMain() on Visual Studio builds, unless we specify the entry point.
Pass the /entry:mainCRTStartup linker flag on Visual Studio builds for
the demo programs so that they can link properly.
https://bugzilla.gnome.org/show_bug.cgi?id=773299
We're mixing a lot of styles in the Meson build files. This is an
attempt at making everything slightly more consistent in terms of
whitespace and indentation.
