[CFLAA] Use raw pointers instead of Optional<Pointer>. NFC.

Using Optional<> here doesn't seem to be terribly valuable, but
this is not the main point of this change. The change enables
us to merge the (now) two identical copies of parentFunctionOfValue()
that Steensgaard's and Andersens' provide.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306351 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed