Fix GCC 12 errors:

    error: 'invoke' is not a member of 'std'
    error: 'cmp_greater' is not a member of 'std'

Fix the linker command error on MacOS with AppleClang 13.1.6.13160021

    Undefined symbols for architecture x86_64:
      "irt::small_vector<irt::hierarchical_state_machine::state, 254>::small_vector()", referenced from:
          irt::hierarchical_state_machine::hierarchical_state_machine() in public-api.cpp.o
      "irt::small_vector<unsigned short, 6>::small_vector()", referenced from:
          irt::hierarchical_state_machine::hierarchical_state_machine() in public-api.cpp.o
      "irt::small_vector<unsigned short, 6>::operator[](int)", referenced from:
          irt::hsm_wrapper::lambda(irt::simulation&) in public-api.cpp.o
      "irt::small_vector<unsigned short, 6>::empty() const", referenced from:
          irt::hsm_wrapper::lambda(irt::simulation&) in public-api.cpp.o
          irt::hsm_wrapper::transition(irt::simulation&, double, double, double) in public-api.cpp.o
    ld: symbol(s) not found for architecture x86_64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)