### 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);
}

```
for (int k = 0; k < args.size(); k++) {
				if (get_scalar_type(args[k]) != args[k] || args[k] == pfunc->arguments[k].type || p_func->arguments[k + 1]->type != Node::TYPE_CONSTANT) {
					
					continue;
				}
				
				ConstantNode *constant = static_cast<ConstantNode *>(p_func->arguments[k + 1]);
				ConstantNode *conversion = alloc_node<ConstantNode>();
				conversion->datatype = pfunc->arguments[k].type;
				conversion->values.resize(1);
				convert_constant(constant, pfunc->arguments[k].type, conversion->values.ptrw());
				p_func->arguments.write[k + 1] = conversion;
			}
			if (r_ret_type) {
				*r_ret_type = pfunc->return_type;
				if (pfunc->return_type == TYPE_STRUCT) {
					*r_ret_type_str = pfunc->return_struct_name;
				}
			}
			return true;
		}
	}
	if (last_arg_count > args.size()) {
		_set_error(vformat(RTR("Too few arguments for \"%s(%s)\" call. Expected at least %d but received %d."), String(name), arg_list, last_arg_count, args.size()));
	} else if (last_arg_count < args.size()) {
		_set_error(vformat(RTR("Too many arguments for \"%s(%s)\" call. Expected at most %d but received %d."), String(name), arg_list, last_arg_count, args.size()));
	}
	return false;
}
bool ShaderLanguage::_compare_datatypes(DataType p_datatype_a, String p_datatype_name_a, int p_array_size_a, DataType p_datatype_b, String p_datatype_name_b, int p_array_size_b) {