add missing "x86_64-linux-natipkg" dependency

Merge to v6.1.1

(cherry picked from commit 079ea21dabce1ffda6e3e5f99da5efd881b4e61b)
fix allocation bug in `equal?` on deeply nested values

Based on the core file, this bug seems likely responsible for the
`raco setup` crash on DrDr for push 29346.

Merge to v6.1.1

(cherry picked from commit 7e984c600957ac5d9ccf366b3f9377e206d56960)
macro expander: fix an internal hash-table traversal bug

This bug could result in weird "cannot re-define a constant: lifted.0.2"
errors, or probably even worse collsisions of definitions, but I think
only in a namespace created from `module->namespace`.

So far, I haven't been able to create a reasonably small test,
because so many things have to line up in just the right way.

Merge to v6.1.1

(cherry picked from commit d4ad0a20e40ec7f7ffa7907470fc7dda76e59c15)
add a description of the bugs in the benchmark to the documentation

please include in the release

(cherry picked from commit ef76c273ea31e866ba4e1758e4747323e7ac9f67)
ffi/unsafe: fix `make-sized-byte-string` on a #f argument

In particular, a #f argument can make sense if the length is 0.
Technically, a byte string's byte array is supposed to be nul-terminated,
but many uses of byte strings get away without that terminator. I've
adjust the documentation to note that `bytes-copy` will work with a
non-terminated byte string.

Merge to v6.1.1

(cherry picked from commit 1cc86d3cea4763d70e4a155e286305215519a23d)