memsec

Rust implementation libsodium/utils.

• [x] memeq/memcmp
• [x] memset/memzero
• [x] mlock/munlock
• [x] alloc/free/mprotect
• [x] Linux only: alloc_memfd_secret/free_memfd_secret functions similar to alloc/free implementation backed by memfd_secret

ref

• Securing memory allocations
• rlibc
• aligned_alloc.rs
• cst_time_memcmp
• [memfd_secret] (https://man.archlinux.org/man/memfd_secret.2.en)