C++ standard

[teuben]

The default C++ on Ubuntu22 is sufficiently far ahead of the de-defacto version that starlab has used.

I recommend we add a new --with-std=c++98 to configure.ac that translates into adding -std=c++98 to CXXFLAGS.
My mknemo build script uses this for now:

CXXFLAGS=-std=c++98 ./configure --prefix=$NEMO/opt

Maybe a later version works as well, didn't go there yet.