### Godot version

4.0.2.stable

### System information

Windows 11, Vulkan, RTX2070 Super

### Issue description

Reading from `VIEWPORT_SIZE` in the `light()` function causes spatial shader to break and renders as default white.

### Steps to reproduce

![image](https://user-images.githubusercontent.com/20043270/236914345-ccd12e83-4431-4a53-b67b-028c8ef5719b.png)

when line 51 is present the fails to compile with the following message in the output log but no compilation errors.

```
servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp:171 - Condition "!shader_singleton->shader.version_is_valid(version)" is true.
  drivers/vulkan/rendering_device_vulkan.cpp:5361 - Condition "!shader" is true. Returning: RID()
  drivers/vulkan/rendering_device_vulkan.cpp:5835 - Condition "!us" is true.
```

commenting out line 51 solves this issue.

[The documentation](https://docs.godotengine.org/en/stable/tutorials/shaders/shader_reference/spatial_shader.html#light-built-ins) states that `VIEWPORT_SIZE` should be available to the `light()` function.

### Minimal reproduction project

N/A
if (depth_pre_pass_enabled) {
								
								
								
								depth_stencil.depth_compare_operator = RD::COMPARE_OP_EQUAL;
								depth_stencil.enable_depth_write = false;
							}
							if (l & PIPELINE_COLOR_PASS_FLAG_SEPARATE_SPECULAR) {
								shader_flags |= SHADER_COLOR_PASS_FLAG_SEPARATE_SPECULAR;
							}
						}
						if (l & PIPELINE_COLOR_PASS_FLAG_MOTION_VECTORS) {
							shader_flags |= SHADER_COLOR_PASS_FLAG_MOTION_VECTORS;
						}
						if (l & PIPELINE_COLOR_PASS_FLAG_LIGHTMAP) {
							shader_flags |= SHADER_COLOR_PASS_FLAG_LIGHTMAP;
						}
						if (l & PIPELINE_COLOR_PASS_FLAG_MULTIVIEW) {
							shader_flags |= SHADER_COLOR_PASS_FLAG_MULTIVIEW;
						}
						int variant = shader_version + shader_flags;
						if (!static_cast<SceneShaderForwardClustered *>(singleton)->shader.is_variant_enabled(variant)) {
							continue;
						}
						RID shader_variant = shader_singleton->shader.version_get_shader(version, variant);
						color_pipelines[i][j][l].setup(shader_variant, primitive_rd, raster_state, multisample_state, depth_stencil, blend_state, 0, singleton->default_specialization_constants);
					}
				} else {
					RD::PipelineColorBlendState blend_state;
					RD::PipelineDepthStencilState depth_stencil = depth_stencil_state;