### 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);
}

```
bool found = false;
					while (builtin_func_defs[idx].name) {
						if (builtin_func_defs[idx].tag == p_block->block_tag && builtin_func_defs[idx].name == identifier) {
							found = true;
							break;
						}
						idx++;
					}
					if (!found) {
						_set_error(vformat(RTR("Unknown identifier in expression: '%s'."), String(identifier)));
						return nullptr;
					}
				} else {
					if (!_find_identifier(p_block, false, p_function_info, identifier, &data_type, &ident_type, &is_const, &array_size, &struct_name)) {
						if (identifier == "SCREEN_TEXTURE" || identifier == "DEPTH_TEXTURE" || identifier == "NORMAL_ROUGHNESS_TEXTURE") {
							String name = String(identifier);
							String name_lower = name.to_lower();
							_set_error(vformat(RTR("%s has been removed in favor of using hint_%s with a uniform.\nTo continue with minimal code changes add 'uniform sampler2D %s : hint_%s, filter_linear_mipmap;' near the top of your shader."), name, name_lower, name, name_lower));
							return nullptr;
						}
						_set_error(vformat(RTR("Unknown identifier in expression: '%s'."), String(identifier)));
						return nullptr;
					}
					if (is_const_decl && !is_const) {
						_set_error(RTR("Expected constant expression."));
						return nullptr;
					}
					if (ident_type == IDENTIFIER_VARYING) {
						TkPos prev_pos = _get_tkpos();
						Token next_token = _get_token();