mesa: Use proper structure for glGet*(GL_TEXTURE_COORD_ARRAY*).

mesa: Use proper structure for glGet*(GL_TEXTURE_COORD_ARRAY*).

The code in get.c that handles this uses ctx->Array.VAO->VertexAttrib,
which is a gl_vertex_attrib_array structure, not a gl_client_array.

The offsets of all fields happened to be the same in both structures, at
least on x86_64.  "Size," "Type," and "Stride" are obviously the same:
both structures start with the same fields, in the same order.

"Enabled" is dicier: there are different fields before it in both
structures, including pointer sized values which might need special
alignment.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Fredrik Höglund <fredrik@kde.org>
Reviewed-by: Brian Paul <brianp@vmware.com>
Cc: mesa-stable@lists.freedesktop.org