Reapply "[analyzer] Accept C library functions from the `std` namespace"

This reapplies f32b04d4i, after fixing
the use-after-free of ASTUnit in the unittest.
https://github.com/llvm/llvm-project/pull/84469#issuecomment-1992163439



Co-authored-by: Balazs Benics <benicsbalazs@gmail.com>