glx: Initialize OpenGL version to 1.0

glx: Initialize OpenGL version to 1.0

The old code in dri2_glx suffered from a typographical error that caused
the default version to be 2.1 instead of 1.2 (minimum required by the
Linux OpenGL ABI).  drisw_glx had a similar error resulting in a default
version of 0.1.

Some driver/card combinations (r200/RV280, i915/915G) don't support
OpenGL 2.1.  These create in some corner cases an indirect context
instead of a direct context when calling glXCreateContextAttribsARB().
This happens because of a bad default value.  To avoid this, just used
the default value specified by the GLX_ARB_create_context specification:

    "The default values for GLX_CONTEXT_MAJOR_VERSION_ARB and
    GLX_CONTEXT_MINOR_VERSION_ARB are 1 and 0 respectively. In this
    case, implementations will typically return the most recent version
    of OpenGL they support which is backwards compatible with OpenGL 1.0
    (e.g. 3.0, 3.1 + GL_ARB_compatibility, or 3.2 compatibility
    profile)"

Refactor all the default value setting to dri2_convert_glx_attribs, and
make sure the correct defaults are set in that one place.

Signed-off-by: Rico Schüller <kgbricola@web.de>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Bugzilla http://bugs.winehq.org/show_bug.cgi?id=34238
Cc: "9.1 9.2" <mesa-stable@lists.freedesktop.org>