[index] For C++ constructors/destructors, add references to the parent type...

[index] For C++ constructors/destructors, add references to the parent type where its name appears in definitions and declarations

Patch by Nathan Hawes!
https://reviews.llvm.org/D30730

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298170 91177308-0d34-0410-b5e6-96231b3b80d8