Searching for "Waiting for unfinished jobs" directly points you to the failure:
For all previous Ubuntu versions the file /usr/lib/x86_64-linux-gnu/libdl.so was provided by libc6-dev but since Impish this package doesn't provide the file any more. What it provides is the static version libdl.a.make[4]: *** No rule to make target '/usr/lib/x86_64-linux-gnu/libdl.so', needed by 'lib/libSMDS.so'. Stop.
Now there are a couple of packages for different architectures that provide the file but none of them puts the file to /usr/lib/x86_64-linux-gnu/.
Now I wonder what library adds a dependency to a file that doesn't exist.