-std=c++11 breaks compilation with boost=1.87.0

[mschubert]

The build/linux/release/Makefile specifies:

C_OPTIONS= -O3 -DNDEBUG -std=c++11

which leads to a compilation error with the current boost library:

/usr/include/boost/math/tools/config.hpp:28:6: warning: #warning "Boost.Math requires C++14" [-Wcpp]
   28 | #    warning "Boost.Math requires C++14"
      |
In file included from /usr/include/boost/math/tools/precision.hpp:15,
                 from /usr/include/boost/math/special_functions/sinc.hpp:19,
                 from /usr/include/boost/math/quaternion.hpp:21:
/usr/include/boost/math/tools/type_traits.hpp:208:12: error: ‘is_final’ has not been declared in ‘std’
  208 | using std::is_final;
      |            ^~~~~~~~

...followed by 100 more errors...

The solution is to remove -std=c++11 (and the check for this being set) or set it to -std=c++14.