glsl: Mark whole variable used for ClipDistance and TessLevel*.

glsl: Mark whole variable used for ClipDistance and TessLevel*.

There's no point in trying to mark partial array access for
gl_ClipDistance, gl_TessLevelOuter, or gl_TessLevelInner - they're
special built-in variables that control fixed function hardware,
and will likely be used in an all-or-nothing fashion.

Since these arrays only occupy 1-2 varying slots, we have to avoid
our normal processing which increments the slot value by the array
index.

(I wrote this code before i965 switched from ir_set_program_inouts
to nir_shader_gather_info.  It's not used by anyone today, and I'm
not sure how valuable it is...the alternative to GLSL IR lowering
is NIR compact arrays, at which point you should use nir_gather_info.)

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>