It's overkill and suffers from annoying false positives that
prevent us from applying the "protected non-virtual destructor"
idiom in several perfectly valid cases. See for instance the
GCC bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102168
The -Wdelete-non-virtual-dtor warning (included in -Wall) is
the preferred alternative and is enough to catch the unsafe
cases without false positives.
Partially reverts 847de408cb
Change-Id: I46ee1f01e7d4e2b125c2c534c6550824ba1de4c0