glsl: count attributes for vertex inputs properly.

This function deals with vertex inputs and fragment
outputs, so we should count the attribute locations
correctly for the vertex inputs.

Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/glsl/linker.cpp

@@ -2466,7 +2466,7 @@ assign_attribute_or_color_locations(gl_shader_program *prog,
          return false;
       }
 
-      const unsigned slots = var->type->count_attribute_slots(false);
+      const unsigned slots = var->type->count_attribute_slots(target_index == MESA_SHADER_VERTEX ? true : false);
 
       /* If the variable is not a built-in and has a location statically
        * assigned in the shader (presumably via a layout qualifier), make sure