mesa: implement clamping controls (ARB_color_buffer_float)

mesa: implement clamping controls (ARB_color_buffer_float)

Squashed commit of the following:

Author: Marek Olšák <maraeo@gmail.com>

    mesa: fix getteximage so that it doesn't clamp values
    mesa: update the compute_version function
    mesa: add display list support for ARB_color_buffer_float
    mesa: fix glGet query with GL_ALPHA_TEST_REF and ARB_color_buffer_float

commit b2f6ddf907935b2594d2831ddab38cf57a1729ce
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Tue Aug 31 16:50:57 2010 +0200

    mesa: document known possible deviations from ARB_color_buffer_float

commit 5458935be800c1b19d1c9d1569dc4fa30a97e8b8
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Tue Aug 24 21:54:56 2010 +0200

    mesa: expose GL_ARB_color_buffer_float

commit aef5c3c6be6edd076e955e37c80905bc447f8a82
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Thu Aug 26 18:12:34 2010 +0200

    mesa, mesa/st: handle read color clamping properly

    (I'll squash the st/mesa part to a separate commit. -Marek)

    We set IMAGE_CLAMP_BIT in the caller based on _ClampReadColor, where
    the operation mandates it.

    TODO: did I get the set of operations mandating it right?

commit 3a9cb5e59b676b6148c50907ce6eef5441677e36
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Thu Aug 26 18:09:41 2010 +0200

    mesa: respect color clamping in texenv programs (v2)

    Changes in v2:
    - Fix attributes other than vertex color sometimes getting clamped

commit de26f9e47e886e176aab6e5a2c3d4481efb64362
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Thu Aug 26 18:05:53 2010 +0200

    mesa: restore color clamps on glPopAttrib

commit a55ac3c300c189616627c05d924c40a8b55bfafa
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Thu Aug 26 18:04:26 2010 +0200

    mesa: clamp color queries if and only if fragment clamping is enabled

commit 9940a3e31c2fb76cc3d28b15ea78dde369825107
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Wed Aug 25 00:00:16 2010 +0200

    mesa: introduce derived _ClampXxxColor state resolving FIXED_ONLY

    To do this, we make ClampColor call FLUSH_VERTICES with the appropriate
    _NEW flag.

    We introduce _NEW_FRAG_CLAMP since fragment clamping has wide-ranging
    effects, despite being in the Color attrib group.

    This may be easily changed by s/_NEW_FRAG_CLAMP/_NEW_COLOR/g

commit 6244c446e3beed5473b4e811d10787e4019f59d6
Author: Luca Barbieri <luca@luca-barbieri.com>
Date:   Thu Aug 26 17:58:24 2010 +0200

    mesa: add unclamped color parameters