Provide a fixit to static_cast for reinterpret_casts within a class hierarchy.

The suggestion was already in the text of the note; this just adds the
actual fixit and the appropriate test cases.

Patch by Alexander Zinenko!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178274 91177308-0d34-0410-b5e6-96231b3b80d8