meson: Cleanup

Change-Id: I1d029117e1a5324f0bf2e013db91c23b08bdbe26
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/meson.build b/test/meson.build
index 6be8abc..df694b6 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -36,6 +36,8 @@
     'fd/mock',
     'fd/ops',
   ]
+elif build_tests.enabled()
+  error('Not testing file descriptor feature')
 else
   warning('Not testing file descriptor feature')
 endif