Various fixes for upcoming release

GLIBCXX assertions are enabled by default on the latest versions of GCC,
this introduces a dependency on the standard libarary which we prefer to
avoid, so we disable them.

This patch makes it explicit that the only supported compilers are GCC
>= 11 and Clang >= 16. GCC 10 doesn't support bitcast and Clang 15
>doesn't support our use of concepts.

Sometimes CMake installs libopenrng in a lib64 directory, so this patch
makes the examples look for the library there as well.