glsl: Consider ubo_load to be a horizontal operation.

Unclear to me whether it actually is a horizontal operation that cannot
be vectorized, but the fact that i965 generates the same code in either
case makes me less interested in finding out.

Cc: mesa-stable@lists.freedesktop.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94199
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/glsl/ir.h

@@ -1686,6 +1686,7 @@ public:
              operation == ir_binop_dot ||
              operation == ir_binop_vector_extract ||
              operation == ir_triop_vector_insert ||
+             operation == ir_binop_ubo_load ||
              operation == ir_quadop_vector;
    }