This way, we can enable the built binaries to print out diagnostic
messages as needed by the values we set via the envvar GDK_DEBUG.
The release configs of the Visual Studio project files follow the
settings of Meson's `debugoptimized` build settings.
Update the NMake Makefiles to invoke glib-compile-resources with
'start /min' so that when gdk-pixbuf-pixdata, json-glib-format
and xmllint are invoked by glib-compile-resources, cmd.exe windows
will not popup whenever these auxiliary tools are invoked, when one
builds GTK with the Visual Studio projects.
This will reduce the distraction that is caused during the time the
source files are generated, as a popup cmd.exe window will disrupt the
window focus as they appear, and will make the process a bit quicker.
