commit 378f8cb5222b63e4f8532c757ce54e4074567e1f added these functions (as stubs) but left them without declarations. this broke some autoconf based software that detected linkability of the symbols but didn't check for a declaration.
the pathnames prefixed with /dev/null/ are guaranteed never to be valid. the previous use of /dev/null alone was mildly dangerous in that bad software might attempt to unlink the name when it found a non-regular file there and create a new file.
patch by Chris Spiegel.
this commit is part of an effort to make more of busybox work out-of-the-box.