GLX: More consistent naming of an AttribArray.
Remove the now unused _AttribList_size.

_AttribPairList_size is still used for WGL's float-based attribs.
Allow float-based attrib_lists as found in WGL.

It also turns out that no "type" member is needed in AttribArray,
so remove it.
WGL: Support float-based attrib_list parameters.

Followup to making it possible in the code generator.
Remove the last helper for the old incomplete attrib_list support.