Add the GLIB_AVAILABLE_IN_ALL annotation to all old functions (that
haven't already been annotated with the GLIB_AVAILABLE_IN_* macros or a
deprecation macro).
If we discover in the future that we cannot use only one macro on
Windows, it will be an easy sed patch to fix that.
https://bugzilla.gnome.org/show_bug.cgi?id=688681
Correspond to GUnixInputStream and GUnixOutputStream. No true async
support though. But that is how the Win32 API is, for files not
explicitly opened for so-called overlapped IO.
The API to create these streams takes Win32 HANDLEs. Not file
descriptors, because file descriptors are specific to the C library
used. The user code and GLib might be using different C libraries.
Also add a test program for the new classes, and a gio-windows-2.0.pc
file.
