Mark 'front()' and 'back()' as noexcept for array/deque/string/string_view. These are just rebranded 'operator[]', and should be noexcept like it is.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@356435 91177308-0d34-0410-b5e6-96231b3b80d8
12 files changed