I updated the test_feature gnuc makefile so it will compile under Linux again, here is the file. All of the tests pass.

Thanks for the updated makefile, and for the confirmation that the tests pass on Linux as well.

I don't have a Linux environment readily available, so I don't usually test that. Though I do test the library on my Mac every once in a while, which ought to be enough most of the time since the platforms are quite similar and both use GNUC as compiler.