i965/nir: Use the nir copy of shader_info to handle gl_PatchVerticesIn

i965/nir: Use the nir copy of shader_info to handle gl_PatchVerticesIn

Instead of using the copy of shader_info stored in gl_program, it now
uses the one in nir_shader. This is needed for SPIR-V because the
info.tess.tcs_vertices_out is filled in via _mesa_spirv_to_nir which
happens much later than with a GLSL shader. The copy of shader_data in
gl_program is only updated later via brw_shader_gather_info but that
is too late.

For GLSL this shouldn't create any problems because the nir copy of
the shader_info is immediately copied from the gl_program in
glsl_to_nir.

v2: updated after commit "i965: Combine both gl_PatchVerticesIn
    lowering passes." (488972) (Alejandro Piñeiro)

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>