In the sqlite3 build, under certain conditions, we ended up with an CG
update order in which an internal function ended up being unreachable
before CallGraphUpdate::reanalyzeFunction was called on it. That
resulted in a segfault as the function did not belong to any SCC
anymore. We now detect this and avoid to reanalyze such unreachable
I failed to simplify the 1.9MB sqlite3.bc file as conversion into .ll,
e.g., as performed by llvm-reduce, causes the problem to disappear.