[MachineOutliner] Move hasAddressTaken check to MachineOutliner.cpp

*Mostly* NFC. Still updating the test though just for completeness.

This moves the hasAddressTaken check to MachineOutliner.cpp and replaces it
with a per-basic block test rather than a per-function test. The old test was
too conservative and was preventing functions in C programs from being
outlined even though they were safe to outline.

This was mostly a problem in C sources.

llvm-svn: 322425