[AST] Follow-up to r297972, add default value for setGetterName/setSetterName if a source-loc is not provided.

Fixes lldb build.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297974 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed