Prevents shader crash on GLES2 if unsupported built-in has been used

servers/visual/shader_language.h

@@ -715,7 +715,7 @@ private:
 
 	enum SubClassTag {
 		TAG_GLOBAL,
-		TAG_ARRAY
+		TAG_ARRAY,
 	};
 
 	struct BuiltinFuncDef {
@@ -724,6 +724,7 @@ private:
 		DataType rettype;
 		const DataType args[MAX_ARGS];
 		SubClassTag tag;
+		bool high_end;
 	};
 
 	struct BuiltinFuncOutArgs { //arguments used as out in built in functions