Missing 'cmp' utility makes build take 10 times as long

I have been doing some work cross compiling qemu for Windows using a minimal Fedora container. Recently I started hitting some timeouts on the CI service and noticed a build of all targets was going over 1 hour.

It seems like the 'cmp' utility from diffutils is used somewhere in the process and if it's missing, either a configure or a make gets run way too many times - I'll try to pull logs from the CI system at some stage soon.

Could a warning or error be added if cmp is missing?