Veracrypt for build under GCC6 required using compatibility flag `-std=c++98` against change default C++ frontend in GCC6.
The C++ frontend now defaults to C++14 standard instead of C++98 it has
been defaulting to previously, for compiling older C++ code that might
require either explicitly compiling with selected older C++ standards,
or might require some code adjustment, see
http://gcc.gnu.org/gcc-6/porting_to.html for details. The experimental
C++17 support has been enhanced in this release.
from: https://gcc.gnu.org/ml/gcc-announce/2016/msg00000.html
