Fix warning and improve description of ignore_parameter test

See https://github.com/swig/swig/pull/2205#issuecomment-1052648190

Examples/test-suite/ignore_parameter.i

@@ -11,6 +11,10 @@
 %typemap(argout) int bb "called_argout = 1;"
 
 %ignore unignorable;
+// Don't let SWIG expand this function with its default parameter: instead,
+// always "require" the version of the function with a single argument, but
+// then ignore it using `numinputs=0`.
+%ignore audi();
 
 %inline %{
 // constant for detecting correct "argout" call

Examples/test-suite/python/ignore_parameter_runme.py

@@ -16,6 +16,7 @@ check(car.astonmartin("foo", 1), 101)
 check(car.bugatti("bar", 2), 8.8)
 check(car.lamborghini(), 101)
 check(car.maseratti(289), 289)
+check(car.audi(), 8.8)  # Typemap overrides default argument
 
 MiniCooper(200, 0)
 MorrisMinor("baz", 0)

Examples/test-suite/ruby/ignore_parameter_runme.rb

@@ -25,6 +25,7 @@ raise RuntimeError unless sc.daimler(0, 1.0) == "hello"
 raise RuntimeError unless sc.astonmartin("foo", 1.0) == 101
 raise RuntimeError unless sc.bugatti("foo", 0) == 8.8
 raise RuntimeError unless sc.lamborghini() == 101
+raise RuntimeError unless sc.audi() == 8.8
 
 # Constructor tests
 MiniCooper.new(0, 1.0)