[HOpenGL] Stable version

[Sven Panne]

After a few (de-)installation cycles I finally figured out the OpenGL
header story for the WinDoze versions of GHC:

  * GHC 5.04 contains a GL subdir with OpenGL headers below include\mingw.
    Those headers seem to come from a Cygwin distribution, despite of the
    misleading pathname.

  * Alas, GHC 5.04.1 and GHC 5.04.2 are not shipped with OpenGL headers.

  * The WinDoze installer packages for *both* GHC 5.04 and GHC 5.04.1 are
    called 'ghc-5-04-1.msi'?! This is where part of my confusion came from.
    I suggest changing this on haskell.org/ghc.

  * As an aside, the GHC 5.04.2 installer comes with superfluous compilers
    and support libraries for C++, Objective-C and Fortran77. Leaving these
    out would reduce the unpacked size of GHC by 6.3MB.  :-)

Some more confusing facts about MinGW and Cygwin:

   * MinGW's headers GL/gl{,u,ext}.h are identical to the ones from Cygwin's
     w32api/GL. The GL/glext.h header is lying about the OpenGL version on
     WinDoze, pretending it's 1.3.

   * MinGW comes with a GLUT libraries, but not with a corresponding
     GL/glut.h header.

What to do in all this chaos? As the simplest short-term solution I've
packaged the following headers into a ZIP file:

    include/mingw/GL/gl.h        (from Cygwin's w32api/GL == MinGW's GL)
    include/mingw/GL/glu.h       (from Cygwin's w32api/GL == MinGW's GL)
    include/mingw/GL/glut.h      (from Cygwin's GL)
    include/mingw/GL/glext.h     (from Cygwin's w32api/GL == MinGW's GL)

It is available at:

    http://haskell.org/HOpenGL/releases/OpenGL-includes.zip

Simply unzip it into the installation directory of GHC 5.04.1 or 5.04.2
(e.g. C:\ghc\ghc-5.04.2 for the default 5.04.2 installation). It would
be nice if upcoming WinDoze installers for GHC were shipped with those
headers.

Cheers,
    S.