[date] Update to 2019-11-08

[qis]

This updates the date port to the latest version.

The HowardHinnant/date@a5c4b4e commit is necessary to use (not just build and install) the library in combination with a recent libc++. The later changes are not necessary, but nice to have.

Portfile changes:

• The ENABLE_DATE_TESTING option is off by default now, so there is no need to set it explicitly.
• The BUILD_TZ_LIB option is off by default now, so it has to be set explicitly.

[qis]

While you review it, the new CMakeLists.txt switched to C++17 by default, so it might actually close #4864.

[JackBoosY]

/azp run

[LilyWangL]

Hi @qis, thanks for your new PR. Here are some regressions from the current CI system:

x64-osx	master	test	notes
date	Pass	Fail	Regression

x86-windows	master	test	notes
date	Pass	Fail	Regression

x64-uwp	master	test	notes
date	Pass	Fail	Regression

arm-uwp	master	test	notes
date	Pass	Fail	Regression

[qis]

@LilyWangL Ah yes. Glad to get useful logs out of your CI now. Congratulations on fixing it!

I've added a backwards compatibility patch for CMake 3.14. It should be removed when vcpkg moves to 3.15 or later.

Will test future PRs with outdated CMake versions.

Where can I find the lowest officially supported version? Is it os=windows, os=osx, and os=linux in scripts/vcpkgTools.xml or should I also respect the even more outdated version for os=freebsd?

[ras0219-msft]

You can ignore the os=freebsd; the lowest officially supported version is os=windows, os=osx, and os=linux.

[ras0219-msft]

LGTM, thanks!