[date] Resolve link error to date::locate_zone

[degski]

I don't know what the solution is, but HowardHinnant/date#398 is the problem.

EDIT: It looks like the port's CMakeLists.txt file does not deal with compiling for C++17 (std is set to C++11), then thereafter (when called), from a program compiled with C++17, now all of a sudden std::string_view is defined, but that overload is not available.

I've for now plugged the file for my purposes, but it should obviously be done correctly (I'm not qualified).

CMakeLists.txt

[MonicaLiu0311]

At present, the upstream has set C++17 in CMakeLists. I successfully build and link to my library after trying it locally.

Fixed by upstream#492, #11968.