dbc0955314
This header first appeared in 4.4BSD and is provided by a number of C libraries including Newlib. Several of our embedded projects use this header and so to make LLVM libc a drop-in replacement, we need to provide it as well. For the initial commit, we only implement singly linked variants (SLIST and STAILQ). The doubly linked variants (LIST, TAILQ and CIRCLEQ) can be implemented in the future as needed.