cgen: add () for | and ^

cmd/v/v.v

@@ -121,7 +121,7 @@ fn parse_args(args []string) (&pref.Preferences, string) {
 				res.out_name  = cmdline.option(args, '-o', '')
 				i++
 			}
-			'-csource' {
+			'-csource', 'backend' {
 				i++ // TODO
 			}
 			else {

vlib/v/gen/cgen.v

@@ -1382,7 +1382,7 @@ fn (g mut Gen) infix_expr(node ast.InfixExpr) {
 		}
 	}
 	else {
-		need_par := node.op == .amp // `x & y == 0` => `(x & y) == 0` in C
+		need_par := node.op in [.amp, .pipe, .xor] // `x & y == 0` => `(x & y) == 0` in C
 		if need_par {
 			g.write('(')
 		}