We only want to include gslist.h here if it was not already included via
including glib.h, as:
* gslist.h should normally be included via glib.h if used outside of
GLib itself.
* This broke Visual Studio builds that use GResources (via
glib-compile-resources.exe) as that would cause the generated code to
include gslist.h directly, which is therefore disallowed.
Symbols on x86 are prefixed with an underscore
but symbols on x64/ARM/ARM64 are not.
Relevant information concerning the prefixes for the architectures
can be found in the vcpkg project [1,2], where arm and arm64 builds
are part of the CI.
Specifically, _WIN64 is defined on Windows ARM64, so this issue is
only visible when building on ARM32.
[1] 08e74979df/ports/glib/fix-arm-builds.patch
[2] https://github.com/microsoft/vcpkg/pull/6116
Whole program optimization is enabled by default in visual studio
release builds, and this causes constructors (for e.g. resources) to be
optimized away as they are not referenced from elsewhere.
This works around this by some pragma magic.
https://bugzilla.gnome.org/show_bug.cgi?id=752837
With this we're not longer exporting the constructor headers, which means
we're not tying ourselves to a macro that might need special tweaking on
a compiler-by-compiler basis.
