### Godot version

4.0b17

### System information

macOS 13.2

### Issue description

The shader function fma, used by the visual shader UVFunc node generated code:
```
// UVFunc:5
vec2 n_in5p1 = vec2(6.00000, 6.00000);
vec2 n_in5p2 = vec2(0.50000, 0.50000);
vec2 n_out5p0 = fma((UV - n_in5p2), n_in5p1, n_in5p2);
```
Does not seem to be defined in the Compatibility renderer, causing shader compilation to fail if it's used with a lot of errors and debug output (10000+ messages as it prints out a lot of engine shader code?). Ending with the relevant errors:
 ```
drivers/gles3/shader_gles3.cpp:242 - SceneShaderGLES3: Fragment shader compilation failed:
  ERROR: 0:928: Invalid call of undeclared identifier 'fma'
  ERROR: 0:930: Use of undeclared identifier 'm_n_out5p0'
  
  drivers/gles3/shader_gles3.cpp:342 - Method/function failed.
```

Simple shader using fma in Mobile:
![Screenshot 2023-02-08 at 09 52 38](https://user-images.githubusercontent.com/17763524/217483066-fe0feab7-72c4-4db7-a44e-041a1ad93f25.jpg)

Switch to Compatibility renderer:
![Screenshot 2023-02-08 at 09 53 27](https://user-images.githubusercontent.com/17763524/217483149-4fdef308-67cf-40d2-8d4a-d72dc7c85e70.jpg)



### Steps to reproduce

- Start a project in Mobile
- Make a shader where you use the fma function, for example the shader below in the reproduction field. Or a visual shader using the UVFunc node.
- Assign the shader to a shader material and apply this to a visible mesh, observe it renders
- Switch project to Compatibility renderer
- See errors and failed shader compilation

### Minimal reproduction project

Minimal test shader, use in Compatibility renderer:

```
shader_type spatial;

void fragment() {
	vec2 n_in5p1 = vec2(6.00000, 6.00000);
	vec2 n_in5p2 = vec2(0.50000, 0.50000);
	vec2 n_out5p0 = fma((UV - n_in5p2), n_in5p1, n_in5p2);

	ALBEDO = vec3(1,0,0);
}

```
if (p_node->type != Node::TYPE_OPERATOR) {
		return p_node;
	}
	
	OperatorNode *op = static_cast<OperatorNode *>(p_node);
	if (op->op == OP_CONSTRUCT) {
		ERR_FAIL_COND_V(op->arguments[0]->type != Node::TYPE_VARIABLE, p_node);
		DataType type = op->get_datatype();
		DataType base = get_scalar_type(type);
		int cardinality = get_cardinality(type);
		Vector<ConstantNode::Value> values;
		for (int i = 1; i < op->arguments.size(); i++) {
			op->arguments.write[i] = _reduce_expression(p_block, op->arguments[i]);
			if (op->arguments[i]->type == Node::TYPE_CONSTANT) {
				ConstantNode *cn = static_cast<ConstantNode *>(op->arguments[i]);
				if (get_scalar_type(cn->datatype) == base) {
					for (int j = 0; j < cn->values.size(); j++) {
						values.push_back(cn->values[j]);
					}
				} else if (get_scalar_type(cn->datatype) == cn->datatype) {
					ConstantNode::Value v;
					if (!convert_constant(cn, base, &v)) {
						return p_node;
					}
					values.push_back(v);
				} else {
					return p_node;
				}
			} else {