If you do use -Werror, provide an easy way for users to disable it via configure flag, environment or make variable. I'm using clang's -Werror -Weverything, wh

If you do use -Werror, provide an easy way for users to disable it via configure flag, environment or make variable. I'm using clang's -Werror -Weverything, which is obviously rather brittle. Building without -Werror is done via make NOWARN=error