Do not attempt to remove the vcl dir if we need the shared object

This avoids a bogus message

	Could not rmdir 'vcl_...': Directory not empty

bin/varnishd/mgt/mgt_vcc.c

@@ -283,10 +283,11 @@ mgt_vcc_fini_vp(struct vcc_priv *vp, int leave_lib)
 	if (!MGT_DO_DEBUG(DBG_VCL_KEEP)) {
 		VJ_unlink(VSB_data(vp->csrcfile));
 		VJ_unlink(VSB_data(vp->symfile));
-		if (!leave_lib)
+		if (!leave_lib) {
 			VJ_unlink(VSB_data(vp->libfile));
+			VJ_rmdir(VSB_data(vp->dir));
+		}
 	}
-	VJ_rmdir(VSB_data(vp->dir));
 	VSB_destroy(&vp->csrcfile);
 	VSB_destroy(&vp->libfile);
 	VSB_destroy(&vp->symfile);