configure: error: --with-hyper but hyper was not found. See docs/HYPER.md.
The problem is that I didn't build Hyper with the appropriate feature flags. The message is confusing because Hyper did exist and was in the right place, but didn't have the correct symbols. We should add a check to configure that the file (libhyper.a) exists in the given directory. If the file exists but the build fails, we can specifically say "hyper was found but it was built with the wrong flags. See docs/HYPER.md"
If hyper is indeed present in the specified directory but couldn't be
used to find the correct symbol, then offer a different error message to
better help the user understand the issue.
Sugggested-by: Jacob Hoffman-Andrews