<string>: Fix handling for char_traits<unicorn> - #4951

<string>: Fix handling for char_traits<unicorn>#4951

Stephan T. Lavavej (StephanTLavavej) merged 7 commits into

microsoft:mainmicrosoft/STL:mainfrom

frederick-vs-ja:char_traits-unicornfrederick-vs-ja/STL:char_traits-unicornCopy head branch name to clipboard