Please add support to use system-provided aws-lc library

[glaubitz]

Currently, aws-lc-fips-sys builds an embedded copy of the C library aws-lc.

Not only creates this a security concern as Linux distributions have to provide security support for every copy of a library on the system. It also makes it more difficult to patch these embedded libraries to address problems like #935.

Thus, please add support for using system-provided C libraries without having to rely on embedded copies.

[justsmth]

Hello! We have this on our roadmap. Hopefully, I can provide more information about it soon.

[jlizen]

This feature would be awesome! My interest here is build-speed related. I'm increasingly seeing aws-lc-sys show up as the long poll in my builds, since so many crates rely on rustls (which defaults to aws-lc). Recompiling from scratch takes ~45 seconds in my builds, of which for maybe ~20 seconds it's the only thing running.