Don't treat non-virtual-dtor as an error.

Some of the new/modified tests explicitly check things about virtual
classes with non-virtual destructors.

Change-Id: Ibd79700a2d4040b1871149035a8ca9eb81ab220c
diff --git a/test/device.cfg b/test/device.cfg
index 0e6ca32..6af2098 100644
--- a/test/device.cfg
+++ b/test/device.cfg
@@ -142,7 +142,6 @@
     '-Werror=address',
     '-Werror=format-security',
     '-Werror=int-conversion',
-    '-Werror=non-virtual-dtor',
     '-Werror=return-type',
     '-Werror=sequence-point',
     '-Winit-self',