### Godot version

v4.0.beta15.official [4fa6edc88]

### System information

Windows 10 (10.0.19045 Build 19045) | Forward+ | Vulkan API 1.3.206 | AMD Radeon RX 6800 XT

### Issue description

If there is a function with arguments within a `.gdshaderinc` file, then this function can not be used in other shaders that include this via a relative include. The error in the other shaders is "Too many arguments for "example()" call. Expected at most 0 but received 1". Using an absolute path for the include resolves the error.

**Note:** The relative include *does* work in the special case of both files being in the project root.

### Steps to reproduce

1. Put a shader and a shader-include file into a subdirectory
2. Write a function with arguments in the shader-include file
3. Include that file in the shader
4. Try to use the function

### Minimal reproduction project

[shader-include-bug.zip](https://github.com/godotengine/godot/files/10508745/shader-include-bug.zip)

const int line = p_tokenizer->get_line();
	const String label = p_tokenizer->get_identifier();
	if (label.is_empty() || !p_tokenizer->consume_empty_line()) {
		set_error(RTR("Invalid undef."), line);
		return;
	}
	if (state->defines.has(label)) {
		memdelete(state->defines[label]);
		state->defines.erase(label);
	}
}
void ShaderPreprocessor::add_region(int p_line, bool p_enabled, Region *p_parent_region) {
	Region region;
	region.file = state->current_filename;
	region.enabled = p_enabled;
	region.from_line = p_line;
	region.parent = p_parent_region;
	state->previous_region = &state->regions[region.file].push_back(region)->get();
}
void ShaderPreprocessor::start_branch_condition(Tokenizer *p_tokenizer, bool p_success, bool p_continue) {