Known problems fixed in GtkAda 2.12.0

- H421-008 GtkAda static library support broken on Windows.
  Problem:    It is not possible to use the GtkAda project file to build a
              application linked statically with GtkAda on Windows. This is
              because the libgtkada.a library is specified using an hard
              coded path into the project file.
  Workaround: Build the application manually or edit lib/gnat/gtkada.gpr to
              fix the offending path.

