[libcxx-commits] [libcxx] [libc++] Simplify vector<bool>::flip() and add new tests (PR #119607)

[Louis Dionne via libcxx-commits]

ldionne wrote:

I'm deferring to @philnik777 's review. I double-checked that all of his comments had been addressed. Thanks!

https://github.com/llvm/llvm-project/pull/119607