These are the final few places in LLVM that use instruction pointers to
insert instructions -- use iterators instead, which is needed for
debug-info correctness in the future. Most of this is a gentle
scattering of getIterator calls or not deref-then-addrofing iterators.
libfuzzer does require a storage change to keep built instruction
positions in a container though. The unit-test changes are very
straightforwards.
This leaves us in a position where libfuzzer can't fuzz on either of
debug-info records, however I don't believe that fuzzing of debug-info
is in scope for the library.
2b1122eaec