Build an example library as a DLL and set up the environment so that it looks
like a system/distro library that can be probed with pkg-config and dynamically
loaded.

Then generate cstubs for it, build an executable that uses those cstubs, and
run the executable that tests the library through the cstubs.

  $ LIBEX=$(realpath "$PWD/../libexample")

This silly looking hack is to make sure the .pc file points to the sandbox. We
cannot set ${prefix} to be interpreted relative to the .pc itself ufortunately
  $ awk "BEGIN{print \"prefix=$LIBEX\"} {print}" $LIBEX/libexample.pc > libexample.pc

  $ DYLD_LIBRARY_PATH="$LIBEX" LD_LIBRARY_PATH="$LIBEX" PKG_CONFIG_PATH="$PKG_CONFIG_PATH:$PWD" dune exec ./example.exe
  4
