Don't call doFinalization from verifyFunction.

Don't call doFinalization from verifyFunction.

verifyFunction needs to call doInitialization to collect metadata and avoid
crashing when verifying debug info in a function.

But it should not call doFinalization since that is where the verifier will
check declarations, variables and aliases, which is not desirable when one
only wants to verify a function.

A possible cleanup would be to split the class into a ModuleVerifier and
FunctionVerifier.

Issue reported by Ilia Filippov. Patch by Michael Kruse.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194574 91177308-0d34-0410-b5e6-96231b3b80d8