1. Some explicit conversions between Inst* and InstList::iterator are needed.

2. llvm::sys::PrintStackTraceOnErrorSignal() has a new argument.

3. A previous CL neglected to plumb in SUBZERO_REVISION for the cmake build.

BUG= none
R=eholk@chromium.org

Review URL: https://codereview.chromium.org/2247253005 .