glsl: Death to array dereferences of vectors!

glsl: Death to array dereferences of vectors!

Now that all the places that used to generate array derefeneces of
vectors have been changed to generate either ir_binop_vector_extract or
ir_triop_vector_insert (or both), remove all support for dealing with
this deprecated construct.

As an added safeguard, modify ir_validate to reject ir_dereference_array
of a vector.

v2: Convert tabs to spaces.  Suggested by Eric.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>