Check that the library component package.conf.d/*.conf file is created (#956)

Had a strange issue where eval of #955 and it might have been caused
by a the nix-tools library seeming to have no `.conf` files.

Since it seemed to go away by itself I think this was a nix GC issue
or something.  Here is some code we could add to the builders to
double check the files are created if it turns out that is not the
case.

Co-authored-by: Rodney Lorrimar <rodney.lorrimar@iohk.io>

builder/comp-builder.nix

@@ -515,6 +515,16 @@ let
       echo The test ${package.identifier.name}.components.tests.${componentId.cname} was built.  To run the test build ${package.identifier.name}.checks.${componentId.cname}.
     '');
 
+    doInstallCheck = true;
+    installCheckPhase = lib.optionalString (haskellLib.isLibrary componentId) ''
+      if test -n "$(shopt -s nullglob; echo $out/package.conf.d/${name}-*.conf)"; then
+          echo $out/package.conf.d/${name}-*.conf " is present"
+      else
+        echo "ERROR: $out/package.conf.d/${name}-*.conf was not created"
+        exit 1
+      fi
+    '';
+
     shellHook = ''
       export PATH="${shellWrappers}/bin:$PATH"
       ${shellHookApplied}