asprintf is a good thing. We should have it.

[bob-beck]

Some of the stuff in openssl/openssl#30575 reminded me of this.

So I added OPENSSL_asprintf() to boring a while back in https://boringssl.googlesource.com/boringssl/+/350f8547cf2101669684ebdb99b49b11fff5e217

Libre has used it since it's inception, and many malloc; strcpy; strcat, strcpy, ... paradigms were
simplified with one call doing the right thing that includes the allocation.

I'm happy to add it, but I might tag the noble sir @esyr to do it since this is their area ;)

[bob-beck]

also - need not be public API, I don't think.. We'd only not use the real one for dealing internally with this on platforms that do not have it.. No need for us to provide it to the world I don't think.

[bob-beck]

Although I guess boring exposed it.. (shrug)

[esyr]

Well, I think it should be exposed, if we want to use it in apps.

[bob-beck]

Sure, that matches what we usually do, although I can not help but wonder if it might not be beneficial for apps to have it's own libc compatibility layer, private to it, and not have libc compatibility provided by libcrypto. But that's for another day :)