cc5a1aad4e
Remove unsafety from sys/unsupported and add deny(unsafe_op_in_unsafe_fn). Replacing `UnsafeCell`s by a `Cell`s simplifies things and makes the mutex and rwlock implementations safe. Other than that, only unsafety in strlen() contained unsafe code. @rustbot modify labels: +F-unsafe-block-in-unsafe-fn +C-cleanup