glsl: Optionally lower TCS gl_PatchVerticesIn to a uniform.

glsl: Optionally lower TCS gl_PatchVerticesIn to a uniform.

i965 has no special hardware for this, so the best way to implement
this is to pass it in via a uniform.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Cc: mesa-stable@lists.freedesktop.org