overwriteFreed

fn overwriteFreed(s: *SafeAllocator, bytes: []u8) void {
    if (!s.check_write_after_free) return;
    // 0x55 is used so that undefined writes of 0xaa are still caught. Another option would be a
    // stream of random bytes seeded by the address, however that makes debugging reads after frees
    // more difficult and has a performance penalty and so is not worth catching slightly more
    // writes after frees.
    @memset(bytes, 0x55);
}