add attribute_unused and include features.h so that we can include libc-internal.h directly and have it work
add attribute_unused and include features.h so that we can include libc-internal.h directly and have it work

joel-porquet/tsar-uclibc,joel-porquet/tsar-uclibc,joel-porquet/tsar-uclibc,joel-porquet/tsar-uclibc