[index] Avoid a crash that happens when looking up a dependent name
in a record that has no definition

rdar://32194921

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@303045 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 7c14490d8a1bffaff51996c6c0619242f35725fa)
3 files changed