Move non-virtual-dtor warning to C++ only
Move non-virtual-dtor warning to C++ only

Causes a warning when building C files.

Change-Id: Ib82134a0bb7a15c88a3edfbdb04d570fde643198

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed