Makes few shader built-ins constant to prevent changing them

servers/rendering/shader_types.cpp

@@ -124,11 +124,11 @@ ShaderTypes::ShaderTypes() {
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["AO"] = ShaderLanguage::TYPE_FLOAT;
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["AO_LIGHT_AFFECT"] = ShaderLanguage::TYPE_FLOAT;
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["EMISSION"] = ShaderLanguage::TYPE_VEC3;
-	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["SCREEN_TEXTURE"] = ShaderLanguage::TYPE_SAMPLER2D;
-	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["NORMAL_ROUGHNESS_TEXTURE"] = ShaderLanguage::TYPE_SAMPLER2D;
-	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["DEPTH_TEXTURE"] = ShaderLanguage::TYPE_SAMPLER2D;
+	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["SCREEN_TEXTURE"] = constt(ShaderLanguage::TYPE_SAMPLER2D);
+	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["NORMAL_ROUGHNESS_TEXTURE"] = constt(ShaderLanguage::TYPE_SAMPLER2D);
+	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["DEPTH_TEXTURE"] = constt(ShaderLanguage::TYPE_SAMPLER2D);
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["DEPTH"] = ShaderLanguage::TYPE_FLOAT;
-	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["SCREEN_UV"] = ShaderLanguage::TYPE_VEC2;
+	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["SCREEN_UV"] = constt(ShaderLanguage::TYPE_VEC2);
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["POINT_COORD"] = constt(ShaderLanguage::TYPE_VEC2);
 
 	shader_modes[RS::SHADER_SPATIAL].functions["fragment"].built_ins["OUTPUT_IS_SRGB"] = constt(ShaderLanguage::TYPE_BOOL);