povray cpprestsdk: apply FreeBSD patches for Xcode 16.3

[cho-m]

Trying to reproduce some failures from #233031 on 15-arm64 runner.

Can't reproduce locally. I have newer macOS and Xcode 16.4 so not sure if this is issue with runner version.

EDIT: Maybe https://developer.apple.com/documentation/xcode-release-notes/xcode-16_4-release-notes#Apple-Clang-Compiler

Fixed: The base template for std::char_traits is restored after being removed in Xcode 16.3; it is still deprecated and is going to be removed in a future release. Restoring the base template allows code that attempts to instantiate char_traits with types that are not provided by the Standard (for example, std::basic_string<long long> and similar) to still compile, giving it more time to transition.
 (149025504)

[cho-m]

Will probably end up dropping bottles during Boost PR and restore them when Xcode 16.4+ is available on runner.

[Bo98]

For povray could try freebsd/freebsd-ports@6133473.
For cpprestsdk there's freebsd/freebsd-ports@2483645 (upstreamed as microsoft/cpprestsdk#1829).

Ultimately, a future version of Xcode is going to break it again anyway even if 16.4 restores compatibility for a while. Haven't checked Xcode 26 yet. But if we're seeing issues more than just these two projects then we could try prioritise a Xcode 16.4 update. We fixed many others before 16.4 was even released.

With that said, both projects are effectively in maintenance mode now so seldomly receive updates or PR reviews.

[cho-m]

I think povray should be fixed if there is ever a new release (3.8+). Too much effort to actually backport the changes so I could try FreeBSD patch.