[C++11] Replacing CXXRecordDecl iterators bases_begin() and bases_end() with iterator_range bases(). Updating all of the usages of the iterators with range-based for loops.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@203803 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify code. No functionality change.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@203804 91177308-0d34-0410-b5e6-96231b3b80d8
Removing some methods which appear to be unused (at least in clang, lld and lldb).

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@203805 91177308-0d34-0410-b5e6-96231b3b80d8