Rework reverse_iterator::operator[] so as not to use the base iterators operator [], which can cause constness problems. Fixes PR17883
Rework reverse_iterator::operator[] so as not to use the base iterators operator [], which can cause constness problems. Fixes PR17883

git-svn-id: 756ef344af921d95d562d9e9f9389127a89a6314@231375 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx