[Bug rtl-optimization/57970] segfault in sched-deps.c

[colanderman at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57970

--- Comment #5 from Chris King <colanderman at gmail dot com> ---
Would a unit test case be acceptable?  That should be an easy way to evince
this bug and I'd be glad to write one.