On 10/5/21 7:11 AM, Robert Pluim wrote:
> Probably. When it comes to gnulib I prefer to leave it to people who
> know what theyʼre doing :-)

We can't wait for *that* (:-), so I charged ahead and installed the 
attached patches into the emacs-28 branch. This fixed the md5_stream 
issue for me.

The key issue here is whether Emacs wants to use cryptography algorithms 
supported by the Linux kernel, if available. I expect that Emacs doesn't 
want to bother, because its use of md5_stream is not that performance- 
or security-relevant and because if we wanted Emacs to use the kernel 
stuff that'd drag in a lot more Gnulib modules which would be more 
trouble than it's worth. Comments welcome of course, since this is a 
judgment call.

I hadn't run into this earlier because I was doing a default 
configure+build, which on my platform didn't use native compilation.