Fix FTBFS (unit-tests) with GCC-11 Instead of fully disabling compiler optimizations, this patch only disables the problematic optimization, so that if new compiler versions introduce new incompatible optimizations it will be easy to spot them and report them upstream.
(re)add install target to CMake This is in part backported from upstream and in part developed in-house. The install target itself has been re-added upstream already, but I've made some tweaks to it in this patch (that I've forwarded upstream)
