st/mesa/glsl: move Version to gl_shader_program_data

st/mesa/glsl: move Version to gl_shader_program_data

This is mostly just used during linking however the st uses it
when updating textures.

In order to store gl_program in the CurrentProgram array
rather than gl_shader_program we need to move this field to
the shared gl_shader_program_data struct.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>