This enables us to have state independent of the liveness of the SILFunction's
that we are tracking.
I also changed the verifier to implement only verifyFull instead of verify to
ensure that when we run with sil-verify-all this only runs at the end of pass
manager pipelines.
rdar://42301529
The invariant is that this analysis should be able to stay in sync with the list
of functions stored in SILModule's function list. If any functions are
added/deleted then analyses can get out of sync with the state of the underlying
SILModule.
Some notes:
1. This is currently disabled by default since there are a bunch of
violations of this in the compiler. I am in the process of fixing violations.
Some examples: the linker and global opt.
2. This is a no-op in non-assert builds.
3. The full verification will only happen when -sil-verify-all is enabled.
Otherwise, we only check that when we delete a function, we had state for the
function.
rdar://42301529
