ghc-boot: Fix metadata handling of writeFileAtomic
Previously the implementation of writeFileAtomic (which was stolen from Cabal) failed to preserve file mode, user and group, resulting in #14017 (closed).
Fixes #14017 (closed).
Previously the implementation of writeFileAtomic (which was stolen from Cabal) failed to preserve file mode, user and group, resulting in #14017 (closed).
Fixes #14017 (closed).