title: Libraries "rt" and "dl" in Cygwin
body: <p>Perhaps this is stupid but I'm unable to find out which package I have to install in Cygwin to fix the following missing libraries:</p>
  
  <pre>
  config.status: creating unix.buildinfo
  config.status: creating include/HsUnixConfig.h
  cabal.exe: Missing dependencies on foreign libraries:
  * Missing header file: HsUnix.h
  * Missing C libraries: rt, dl
  </pre>
  
  <p>Any ideas or how do you generally find out which package to install when you get feedback that file xxx is missing (I remember that in gentoo this was quite straightforward)...</p>