Newer versions of patchelf (noticed with 0.15) require a C++17 compiler.  We
need to stick with the older version until BRL-CAD's minimum C++ support
requirement (currently at C++14) is bumped up to C++17.

Although it is enormously heavier, in the connotation of elf binary editing it
is worth making a note about the LIEF project:  https://lief-project.github.io/
It's a very large C++ build (as opposed to a single, easily built file with
patchelf) so it's not a great candidate for bundling.  That said, it comes up
when possible alternatives to patchelf are discussed and would be a possible
alternative to explore should that ever become necessary.

