Do not swallow installation errors

[andreasabel]

Errors during installation e.g. via ghcup should be lifted to the user rather than swallowed, to enable debugging (e.g. to find out which prerequisites may be missing).

E.g. when attempting to install ghc-8.2.2 on ubuntu-22.04 (via ghcup), one sees only this:

[ Info  ] Unpacking: ghc-8.2.2-x86_64-deb8-linux.tar.xz to /home/runner/.ghcup/tmp/ghcup-6d11b83f58858e08
  [ Info  ] Installing GHC (this may take a while)
  
  [ Error ] Process "gmake" with arguments ["DESTDIR=/home/runner/.ghcup/tmp/ghcup-28ddbf5[38](https://github.com/andreasabel/unix/actions/runs/3624403077/jobs/6111349578#step:3:40)ab31e65",
  [ ...   ]                                 "install"] failed with exit code 2.
  [ Error ] Also check the logs in /home/runner/.ghcup/logs

https://github.com/andreasabel/unix/actions/runs/3624403077/jobs/6111349578#step:3:52

Lifted from: https://github.com/haskell/unix/pull/266#discussion_r1040654412