configure produces misleading error message for some invalid arguments

If configure is called with certain invalid command-line options, it gives a misleading error message which makes it very difficult for the user to figure out what they did wrong.

For example, if you run

./configure -no-make examples

the configure script should complain that it doesn't know what "-no-make" is (the correct option is "-nomake"). However, instead configure complains that it doesn't know what "examples" is, which makes the user think that "-no-make" is fine and "examples" is wrong.