When a function-local value with function-local metadata uses gets RAUWed with a

non-function-local value, it may result in the metadata no longer needing to be
function-local. Check for this condition, and clear the isFunctionLocal flag, if
it's still in the uniquing map, since any node in the uniquing map needs to have
an accurate function-local flag.

Also, add an assert to help catch problematic cases.

llvm-svn: 113828