devel/folly: remove libc++ 19 workaround

For bug 281499 we added a workaround for the peekView() method
returning a std::basic_string<uint8_t>, which is no longer supported
in libc++ 19 and later.

However, upstream folly has consolidated the peek and peekView
methods into just peek, and is now returning a `std::span<uint8_t
const>` instead [1], so the workaround is no longer needed.

Remove it, and bump PORTREVISION so dependent ports get rebuilt. In
particular, I was looking at a build failure of net/mvfst which was
occurring in the folly headers, due to the peek() method being
unavailable.

[1] https://github.com/facebook/folly/commit/3f21ed6dd97f36ca6653b16d5b086b8b8a7efebc

PR: 282522
Approved by: yuri (maintainer)
MFH: 2024Q4