Stop all the Decl classes poking at Redeclarable's data member directly, and make getNextRedeclaration follow the pattern of its friends getPreviousDecl and getMostRecentDecl.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208467 91177308-0d34-0410-b5e6-96231b3b80d8