shader: keep pixel helper lanes out of the EXEC and VCC words

src/graphics/shader/recompiler/backend/spirv/spirvEmitterInternal.h

@@ -146,6 +146,7 @@ struct EmitterState {
 	const IR::Block*           current_block                         = nullptr;
 	uint32_t                   pixel_valid_mask_variable             = 0;
 	uint32_t                   subgroup_local_invocation_id_variable = 0;
+	uint32_t                   helper_invocation_variable            = 0;
 	uint32_t                   per_vertex_variable                   = 0;
 	uint32_t                   point_size_variable                   = 0;
 	uint32_t                   clip_distance_variable                = 0;